| Control Protocols for Lighting Systems |
Taken from: http://www.nurohman.pk.cx/lights_control_interface.htm
Light control interfacesIn almost all stage lighting situations, luminiares are not used constantly at full power. are generally required to fade in and out, and to be used at different brightnesses, or intensities, at different times under control of lighting operator. The actual dimming is done using the light dimmer, but it needs to be controlled in some way, usually form remote location. The control desk, or simply the desk, is the front-end of the lighting control system, and provides an interface between the dimmers and the operator. The state of each dimmer can be changed from the desk, thereby controlling the output from the luminaires. The control desk must communicate with the dimmers in order for the changes made by the operator to take effect on the stage. There are many communication system in use between the lighting desk and the dimmers. There are both analogue and digital systems in use. Analogue systems use a control signal that varies in voltage or current in direct relation to the required intensity. Digital systems use control signals that send the required control level numerically for each channel. The control information could be communicated to the dimmers by using one control wire for each channel: this is called multicore control. Alternatively, each control channel can be instantaneously measured, and the resulting values sent down a single control wire to the dimmer in sequence. This procedure is called multiplexing. Digital systems are more reliable than the analogue equivalent, faster and can be used for more accurate controlling. Besides light dimmers digital light control protocols (most often DMX-512) are used to control devices light intelligent lighting (like roboscanners), foggers and many other lighting devices.
General information
DMX 512DMX is a lighting industry standard way of controlling lighting equipment. The whole idea behind DMX as a standard is that it allows equipment from one manufacturer to talk to that made by another. DMX-512 allows for one controller (like a lighting desk)to control many lights. DMX is limited to controlling 512 separateparameters, that's where the name DMX-512 comes from. DMX-512 is a protocol for controlling (at a basic level) the brightness oflights in a theatre (it is vary capable and can be used for controlling moving lights, smoke machines, strobe lights etc.). It basically consists of one 8-bit (on or off) signal for each light whichsets the brightness level (0-100%) of the light to one of 256 levels. DMX-512 is the standard interface and protocol used in the theatre and entertainment industry. DMX-512 allows control systems to communicate with dimming systems, automated luminaires, color scrollers and with other equipment. Equipment from different manufacturers can be connected toghether nicely and they work together. Practically any DMX-512 control board can be connected to any dimemr or other equipment with DMX-512 interface. DMX is pretty straightforward as a protocol, there are some details at the bit level regarding frames and packets, but they are typically not of concern to the general user. More importantly, DMX fundamentally provides 512 channels of 8-bit resolution (0-255) level control (which constitue a DMX 'universe' of which various gear supports various numbers.) DMX runs over a cousin of our familiar serial port (RS-232) known as RS-485 allowing for up to a (theoretical) 4000 feet cable run (around 1200 meters). In the practical systems is is not a good idea to use longer than around 250 meter cables (realiabity drops on very logn cables). The transmission rate is fixed at 250 kbaud. Electrical characteristics are accoding RS-485 standard. Accroding to RS-485 there can be up to 32 devices daisy-chaines to one line, and in DMX-512 system if you need more you need to use signal splitters or repeaters (or use some new devices with special high impedance inputs that allow up to 256 devices on one cable line). A working DMX rig typically consists of a DMX-enabled controller (lighting board or computer,) cabling, one or more DMX addressable dimmers and lights plugged into AC outlets on the dimmers. Since DMX is really just a bunch of values associated with channels, often channels are used to select a gobo, select a gel, set an X-axis postion, set a Y-axis position, set a strobe rate or do some other task. Many/most of the DJ/Club scanner head lights are DMX these days, allowing for a variety of sync'd movement and chase activity. DMX512 is connected using a daisy-chain methodology where the source connects to the input of the first device, the output of the first device connects to the input of the next device, and so on. The standard allows for up to 32 devices on a single DMX link. The DMX512 communications protocol is very simple and robust. DMX512 was created in 1986 by the United States Institute for Theatre Technology ( USITT ) as a standardized method for connecting lighting consoles. It was revised in 1990 to allow more flexibility (this is the version in use today). The Entertainment Services and Technology Association ( ESTA ) has assumed control over the DMX512 standard. ESTA is making revisions to clarify and further extend the standard. Special care is being taken so that existing DMX512 equipment will work under any new standard. Although the DMX512 standard is being updated, existing equipment will still work the same under any new revision. DMX512 is designed to carry repetitive control data from a single controller to one or more receivers. This protocol is intended to be used to control dimmers, other lighting devices and related non-hazardous effects equipment.Since this Standard does not mandate error checking, DMX512 is not an appropriate control protocol for hazardous applications. So do NOT use DMX-512 to control devices like moving platforms or pyrotechnics. Officially DMX is carried on 5 pin connectors, which carry the data(RS485) on pins 2 & 3, screen (and common mode reference) on 1. Thereis a second data link on pins 4 & 5 the format of which has never beenwell defined and it is seldom used in practice.This means that at an electronics level, the signal is sent through 5-core cable (but only 3 are ever used) consisting of 0v, +ve and -ve signal wires. Cable for DMX-512 installations should be 110 ohm impedance shielded twisted pair cable. A normal microphone cable (shielded twisted pair) works OK for short runs, but can cause problems in long runs (so using it is not recommended). In DMX-512 world there has been a long debate on 3-pin vs 5-pin connector.The ofifcial standard says 5-pin connector.Unfortunately some manufacturers use a cheaper 3-pin XLR connector instead of standard 5-pin. Cheaper/budget lighting kits (like many disco effects) are almost always 3 pin, probably because the plugs are cheaper!It seems that 3 pin is becoming the modern de-factor norm (although not conforming to the DMX512 standard) and 5 pin is becoming more unusual. Current Martin kit uses 'pin 3 +ve' but older Martin stuff is the other way round. It'stherefore worth carrying 'change-over' connectors as well as 3-to 5-pinadaptors if you are workign with systems consisting of components frommany different manufacturers. Standard DMX-512 connector (5-pin XLR) wiring is: Use of 3-pin connector is not defined in the DMX-512 standard, but the industry de-facto pinout for 3-pin XLR connector is the following: DMX512 uses EIA-485-A (commonly refered to as RS485) which is abalanced system. Normative references for electrical specifications at ANSI/TIA/EIA-485-A-1998 Electrical Characteristics of Generators &Receivers for Use in Balanced Digital Multipoint Systems.The electrical specifications of DMX-512-A standard are those of EIA-485-A with some minor exceptions. The DMX-512 interface is electricallyRS-485 bus where there is one transmitter all the time transmitting andmultiple receives along the bus. There is always one transmitter (usually lighting desk or signal repeater) and there can be up to 32 receivers in a single bus.The signal voltage is is between the 2 data lines (pin 2 & 3). The difference between the pin 2 and 3 voltages is what isimportant: data high (digital 1)is if pin 3 is at a higher voltage than pin 2,data low (digital 0) is if pin 2 is at a higher voltage than pin 3.Typicaly the pin 2 and 3 are at either +5 or -5 Volts, but the RS485limits are +12 and -7 Volts. In other words, the data is carried over a twisted pair (connected topin 2 & 3).The transmitting device has a RS485 driver (transmitter) connected topins 2 & 3, and transmits uses +5 and 0 volt levels with respectsto the transmitting devices ground. In receiver side pins 2 & 3 need to be within a few volts with respect tothe receivers 0V reference. (pin 1) There must be a difference of at least 200mV between pins 2 and 3 for the logic state to be reliably detected.The main advantage of using a twisted pair is the ability accept acertain amount of common mode voltage (external noise/interference)and still get the data through. However there are limits to muchcommon mode voltage it can accept, and the cable screen is used tohelp limit how much gets onto the data lines. The DMX512 standard that is not clear is exactly how pin 1 (shield ground)should be used. There are guidelines to manufacturers on how to implement electricalisolation between devices. There is an ideal situation discussed, andalternatives, but unfortunately not every manufacturer has implementedthe ideal. Ideally, the shell of the connectors should be connected to thechassis of the device its plugged into.The cable screen should be connected to pin 1 at both ends, with thetransmitting device provide a connection to ground. The receivingdevice provides no connection to avoid problems with devices havingdifferent ground references. The wiring for what DMX-512 is designed to is 120 ohm shielded twisted pair wiring. In practice DMX-512 works very well on wiring that has impedance at 100-120 ohms range, meaning that is can be used with nowadays common 100 ohm wiring. DMX-512 is designed to use 5-pin XLR connectors, but some implementations use 3-pin XLR connectors. It is also possible to use CAT 5 wiring to carry DMX512 signals. In response to a perceived industry requirement for lower cost DMX512 cable installations, the DMX-over-Category 5 Cable Task Group was formed by ESTA�s Control Protocols Working Group (CPWG) at the January 1998. Accoding the performed tests the Category 5 cable, or "generic premises cable" as it has become known, could be used as a low cost substitute in permanently wired DMX512 installations. It should be noted that while the nominal impedance of Category 5 cable is normally quoted as 100 ohms this is referenced to signals in the 10 to 100 MHz range. The Category 5 cable is also specified as having an impedance of 107 ohms at 256 KHz. This has been verified in measurements by ESTA Control Protocols Working Group. It can be suggested that the minimal reflection from the transition between Category 5 and low capacitance 120 ohm EIA-485 cable is too small to be of any noticeable effect in DMX512 transmission and reception. The use of IEC 60603-7 8-position modular connectors (commonly referred to as RJ45 type connectors � plugs/jacks) and associated punchdown terminal blocks shall be limited to connections that are part of a fixed installation and not normally accessible except to qualified, authorized users, nor intended for regular connection and disconnection. The wiring for RJ-45 connector is the following: A DMX network is restricted to 32 devices in a daisy chain (includingsource), and the far end of the network should be terminated witha 120R resistor between pins 2 & 3. If more than 32 devices needs tobe connected, suitable active signal repeaters and/or splitters needsto be used to split the wiring to parts with less than 32 devicesin each part.For reliable operation of DMX-512 system use right kind of cable. DMX may, or may not, work with microphone cable. This depends on the cable and on the run lengths. So microphone cable is not recommended. DMX512/1990 suggests Belden 9841/2 and Alpha 5271/2 cables, depending on if you want one or two pairs.There are many other cables around which work well with DMX512 system. You need a shielded cable approved for EIA-485 use. You are looking for a cable with shielded twisted pair construction and impedance in 100-120 ohms range. Conductors connected to connector pins 2/3 and 4/5 should be twisted together. At 250K bits per second (DMX-512 data rate) the max cable length is about 1000 ft for DMX512 in good conditions. The DMX512 communications protocol is very simple and robust. The protocol used in DMX-512 bus is similar to normal serial communications(like RS-232 with 8 data bits + 1 stop bit) and operates at 250 kbps speed. DMX-512 is basically serial transmission via rs485 with 250KBit with 8N2 (8 data bits, 1 start bit, 2 stop bits) format. Transmitting DMX-512 data involves transmitting a reset condition (indicating the start of a new "packet"), a start code, and up to 512 bytes of data. A frame start is indicated with 88 �s break (low) (typical value) followed by 4 or 8 �s mark (high). Then a config byte follows (normally 0) and up to 512 data bytes. Normally data packets are transmitted continuously. As soon as one packet is finished, another can begin with no delay if desired (usually another follows within 1 ms, but it can take longer if needed). A NULL START Code identifies subsequent data slots as a block of un-typed sequential 8-bit information. Packets identified by a NULL START Code are the default packets sent on DMX512 networks. Each NULL START Code packet contains no formal data or addressing structure. The device using data from the packet must know the position of that data within the packet. There is no guarantee that all NULL START Code packets will be delivered to all devices. Data sent using NULL START Codes should be of a type where loss of packet does not greatly affect the operation of the device. Dimmer level data should be sent in NULL START Code packets. Valid dimmer levels shall be 0 to 255 decimal (00 to FF hexadecimal) representing dimmer control input. Value 0 shall represent a dimmer output of OFF or minimum and 255 shall represent an output of FULL. A dimmer shall respond to increasing the DMX512 slot value for 0 to 255 by fading from its minimum level (off) to its maximum level (full). If nothing is changing (i.e. no lamp levels change) the same data will be sent out over and over again. The DMX-512 equipment expect see that constant flow of data. The general advice is nowadays that those NULL START packets should be sent in such way that the data in all used dimmer channels are updated at least once a second. Typically the data rate on updates is in order of tens of timer per second (for example 50 updates per second). The DMX-512 system just sends the data to the dimmers with the minimum framing information with no error correction or checking information. This means that DMX signal has absolutely no fault tolerance or error correction/detection. Because the data is sent over and over again, randoms error do not cause typically serious problems (get corrected quicly). Because DMX-512 system does not have any error detection or correction systems, it should not be usd to control devices that can be dangerous if they do somethign unexpected with strange data. Not all 512 channels need to be output per packet, and in fact, it is very uncommon to find all 512 used. For example, most simple lighting consoles only output 16 channels or less. The fewer channels are used, the higher the "refresh" rate. DMX needs to transmit all Channels up to the highest Channel-number used. So in theory if you leave gaps in your DMX numbering it won't hurtanyone but it will lower your refresh rate (more channels to transmit, so at fixed speed the transmissions take more time andthus you get less repeats per time interval.) In practice you don't have this amount of choise, because on nearly all lighting control desks the number of dmx channels is fixed and the refresh rate is fixed. On really posh and expensive control desks you can go into the setupand alter the maximum DMX channel transmitted and therefore increasethe refresh rate. DMX is a very accurately timed stream of repeating data that loops continuously. To create this continual stream of data at 250,000 bits per second takes alot of processing power and finely tuned software, and as such most commercial PC to DMX modules use on board memory and a processor to churn the data out continuously leaving the PC free to work on level sand update the module as required. The communications path for DMX-512 system shoudl be well built to guarantee error free data transmission. Error free data transmission is needed for reliable operation, because DMX-512 does not include any error detection or error correction capabilities in it. This means that if some error happens on the signal on the line, then one dimmer channel some dimmer channels receive incorrect values. Random errors that happen very rarely do not cause too much problem, because the data sent to dimmers is repeated very often (typically tens of times in second). If the dimmer gets wrong data at one data packet, the next packet with correct value will make the dimmer setting right again. So the transmission errors typically do not cause any noticeable problems in light controlling, usually at works cases maybe some random flashing of lights. DMX controlled dimmers either hold the last value or go to zero when a control signal is lost (i.e. when someone turns off the board with the dimmer packs still on). Because DMX-512 does not have any error control or detection capabilities, it should not be used in any application where the reception of wrong control value can cause permanent damage or danger (for example you should not use DMX-512 to control mechanical movemement of any heavy objects). In order to provide for future expansion and flexibility, DMX512 makes provision for 255 additional non NULL START Codes (1 through 255 decimal, 01 through FF hexadecimal), henceforth referred to as Alternate START Codes. Where it is required to send proprietary information over a DMX512 data link, a packet starting with a registered Alternate START Code shall be used. A DMX512 transmitter interleaving NULL START Code packets with Alternate START Code packets shall send a NULL START Code packet at least once per second. DMX512 processing devices or any device that receives and re-transmits DMX512 shall state in the manual for the product how they process Alternate START Code packets. The devices can: The receivers for DMX-512 needs to be carefully designed, because a DMX512 receiver MUST properly decode ANY possible DMX512 transmitter. If the standard does not say that a transmitter can't do something someone has designed one that does! All receiving devices other than in-line processing devices shall process the START Code and differentiate between those packets with NULL START Codes and those with Alternate START Codes. Devices shall not ignore START Codes by assuming that all packets received are NULL START Code packets. The original intention of using DMX512 for controlling dimmers only , has now been stretched to include a whole range of equipment. The 8-bit data structure, which was originally used to specify 256 levels of dimming only, is now also used to define many different parameters in different equipment. Typical applications include mirror position and gobo position on moving mirror light instruments, gelstring position on color changers, shutter position and focus motor position on many intelligent light instruments, smoke machine, sometimes even laser effects and RC servo motors. Equipment for generating DMX512 have also taken different forms. Nowadays you can most often see it done with lighting consoles or with a standard PC that has suitable adapter. In addition to those applications use back-up equipment for consoles, architectural lighting controllers and test instruments or DMX multiplexor (takes in . In addition there are special equipment with receive and transmit capabilities: lighting protocol converters (converts between DMX-512 and some other protocol), DMX multiplexors, DMX de-multiplexors, DMX splitters, intelligent DMX-512 signal combiners etc. The console converts data collected by it from the various tactile controls on it into a 8 bit form using Analog to Digital converters or other devices and then computes the required output data. The PC software works using the same principle but uses software control of the parameters (usually either GUI or control algorithm). Not all 512 channels need to be output per packet, and in fact, it is very uncommon to find all 512 used. For example, most simple lighting consoles only output 16 channels or less. The fewer channels are used, the higher the "refresh" rate. It is possible to get DMX512 refreshes at around 1000 times per second if only 24 channels are being transmitted. If all 512 channels are being transmitted, the refresh rate is around 44 times per second. DMX SPLITTERS generally provide multiple DMX outputs from one input and can drive a large number of units. DMX MERGE units take two or more DMX512 inputs and merge them into one DMX output stream placing one input stream AFTER the other. DMX MIX units take two or more DMX512 inputs and mix them together channel to channel and produce one DMX512 output. The mixing is usually done in the HTP (Higest Takes Precedence) mode, but some devices can also be programmed to work using other algorithms. There are various ways how different light instruments handle the received DMX-512 data: There are some equipment that you should not control with DMX-512. Infact , any thing which compromises the safty of human (or animal !) lives due to failure to recieve and interpret DMX512 correctly, is prohibited. The following equipment are SOME of many which are prohibited from using DMX512 as a trigger source as specified by the standard: pyrotechnics, set shifting equipment and truss motion control. DMX512 data link works quite reliably when properly used, but there are some DMX512 "gotchas" - general aspects of DMX usage to watch out for. In reality, things like dropped bits occur very rarely; dropped channels almost never occur. When you add the "continuous transmission" aspect of DMX512, data link errors are essentially unnoticed. As long as good quality cable is used, and as long as the end of the data link is terminated, you should never see any of these problems. The SIGNALING in DMX is a "real" standard - virtually anything can coexist with virtually anything else and DMX will control it all and things stay out of each other's way nicely. Up to 512 devices, or functions on a device, can be controlled with 8-bit resolution. All channels are continually being "refreshed", which increases safety. Although the DMX512 standard is being updated, existing equipment will still work the same under any new revision.
General information
Technical information
DMX-512 circuits
DMX-512 control software and information on products
AMX192AMX192 is a control protocol standard for dimmers first introduced around 1975 as Strand proprietary multiplexed dimmer control system. This sytem became widely used with Strand's extremely popular Light Palette and CD80 dimmers that first appeared in 1979. The AMX192 standard, adapted by the United States Institute for Theatre Technology, is non proprietary and may be used by all manufacturers. The AMX192 standard was introduced at 1985. The origins of this standard come from a control protocol originally developed by Strand Lighting (Strand Century Inc.). This protocol is used by a large installed base of equipment manufactured by Strand and many other manufacturers. AMX192 uses a small twisted pair cable to communicate with a maximum of 192 dimmers. Depending upon the type of console, a single AMX192 data line can handle either 96 or 192 dimmers. Dimmer levels (0-5V) are sent sequentially on one wire, referenced to a signal common wire that the other conductor is paired with. A synchronizing clock signal is sent differentially on a second pair of wires. The data signal is 'de-multiplexed' (usually at the dimmers) resulting in individual 'analog' control signals (usually 0-10 volt, DC). When AMX first appeared on Strand products, it used the tiny Switchcraft TA4 connector. Its pinout was clock- on pin 1, common on pin 2, clock+ on pin 3 and mux analog on pin 4. Many rental companies have replaced with connector with 4-pin XLR connector. The standardized AMX-192 uses 4-pin XLR connector with the following pinout: The name AMX192 would incate that this USITT analog multiplex would be 192 channel system, but some sources indicate that AMX192 would be able to support up to 384 channels. Because the original protocol has undergone many slightly different versions. There are substantial differences between the receive timing and the transmit timing. New controllers adhering to this standard must produce a signal acceptable to a wide variety of dimmers, and new dimmers must be able to listen to a number of different controller signals. As an example, note that new controllers should provide a wide "analog valid" window, but new dimmers must be able to cope with the differences in existing consoles, and use a narrow "sample window". Although widespread adoption of this Standard is sought by USITT, compliance with the standard is strictly voluntary. One real gotcha with this multiplexed analog schemes is that the cable radiates a fair amount of interference, and so wireless intercomms can get blocked if you are close by. Anyone who has dealt with AMX192 gear for any length of time will tell you that they've had more than their share of problems getting things to communicate properly. No one console, for example, will talk to all receivers out there, and vice versa. The age and condition of receiver cards and power supplies can affect how well the data link works. The type and length of cable can also be a factor when changing to a different transmitter, such as a protocol converter. Designers of new AMX controls usually pick a set of signal timing parameters that are known to work well with most of the existing dimmer racks; you might just be one of the unlucky ones that gets a mismatch. AMX192 has been very widely used in USA markets, both in theatrical and architectural markets. Virtually every North American Strand product designed until very recently included at least one AMX port. As well, a number of their competitors made compatible products over the years AMX192 is virtually non-existent outside of the U.S. and Canada
Microplex (MPX)
As for the control system for the dimming system, today's industry-wide lighting protocols are multiplex (MPX) and DMX-512. Multiplex is known by a variety of names by different companies; it may be called microplex or LMX-128. This communication signal is normally transmitted from your lighting console to your dimmer via a standard microphone cable. Multiplex can offer a maximum total of 128 channels, and the distance between the console and the dimmer should not exceed 125 feet. If your application can accept these limitations, then multiplex is a valid option. The Micro-Plex (MPX) method is aimed at low-cost, short-run, dimmer control applications where standard XLR mic cables can be used with the dimmers and the controller chained in a way that's very similar to MIDI communication. NSI Micro-plex is capable of supporting up to 100-128 dimmer channels. However, the more channels, the slower the refresh rate. NSI Microplex (MPX) is proprietary control protocol used by NSI (Leviton). Some devices from some other companies support this protocol also. The pinout for Microplex 3-pin XLR connector is the following: There are two basic Microplex variants: NSI's version normally supports 64 dimmers, but in certain cases does 96; the Leprecon and Lightronics versions support 128 dimmers. The version used by Lightronics is called LMX-128. The 3 companies supporting this protocol seem to agree on almost everything but basic signal timing parameters, making interoperability a bit dicey. They all use 3-pin XLRs wired as follows: common on pin 1, console power on pin 2, and signal on pin 3. The mux control signal is 0-10 volts.
0-10V DC voltage controllingDC voltage control is very much used in simple light effects and small light dimmer systems. It is a very simple and easy to understand system which can be troubleshooted with just a multimeter. The most commonly used DC based light controlling interfaces are 0-10V control for light dimmers and 1-10V control used to control dimmable electronic fluorescent lamp ballasts. Strand, who pioneered desks with semiconductors, decided on their 0 - -10V control back in the days of p-n-p germanium transistors, when this was natural. Being stubborn, they stayed with this protocol long after it was out of date. Other manufacturers in the industry have used different voltages, but have later sellted to 0..+10V control voltage range. This type of multicore analogue systems were prevalent before digital DMX-512 control became more popular in large systems. In multicore analogue system the console was physically connected on a channel by channel basis to the dimmers. Most modern light controlling desks still emit 0 - +10V, on their analogue lines (usually 15-pin D-connector). Very many modern light dimmers can accept 0-10V control voltage in addition to DMX-152 controlling. For example many 6-channel dimmer packs use 8-pin Bleecon connector (8-pin DIN or 8-pin XLR) for 6 channel analogue 0-10V control voltage. Bleecon connectors ("Bleecons", by Belling Lee) are widely used on dimmer packs of six or less channels for analog control input. The Bleecon is basically an 8 pin DIN plug and socket. The sockets will accept ordinary 8 pin DIN plugs, and also those with a locking ring. The most often pinouts for this Bleecon connector is the following:
There are also other connectors types in use. Dimmers or receiving devices shall use connectors with male contacts (pins). Controllers or sending devices shall use connectors with female contacts (sockets). If suitable connectors are not available in both sexes, the same connector may be used on dimmers and controllers. For most multipin connectors are wired in such way that the different control channel signals start at pin 1 (channel 1 on pin 1, channel 2 on pin 2, etc.) and the highest number pin is signal common. Sometimes several of those highest number pins are used as ground, and sometimes free pins between highest used channel and ground pins are used to supply power though te cable (usually around 12-24V range). Pinout of all control connectors are often labeled adjacent to connector showing all pin assignments or listed on the equipment manual. Typical multi-channel light controlling system which uses 0-10V DC controlling uses thick multicore cables containing a core for each channel, as well as power supplies and ground leads. 0 to 10V cables can be almost any type of conductor or cable. Many DC controlled light control systems (not all) can be connected in parallel in highest takes precedence (HTP) manner. This refers to the way in which a channel is controlled. When a channel is controlled by two or more sources (for example, if two sub-masters on a lighting desk contain the same channel) the highest value is used. HTP channels are normally used for controlling intensity. The standard approach in 0-10V controlling is that the controlling source (lighting desk) supplies power to the line and the receiver (dimmer) just looks at the voltage it gets. The control signal sources have typically their output quite low impedance (1-5 kohm typically) while the devices to be controlled have typically high input impedance (typically around 47 kohms, but can be lower on some some devices). In 0-10V analog lighting control systems the dimmers typically create a ramp signal (looks like |\|\|\|\|\|\|\|\, goes linearly from 10V to 0V and then quickly back to 10V during mains power zero cross). The dimmer has a comparator circuit that triggers a signal if the two input voltages are the same. The comparator circuit circuit ompares the control voltage to the ramp signal that falls from 10 to 0 volts over time of one half cycle of mains power. Example: Control desk "sends" 8V to the dimmer, because it should dim the light to 80%. When ramp signal reaches 8V, the comparator signals the load part of the dimmer (where the lamps are attached) to start the current. The American National Standards Institute's Board of Standards Review approved E1.3-2001, Entertainment Technology - Lighting Control Systems - 0 to 10V Analog Control Specification, on 21 March 2001, is a standard for using DC voltages from zero to 10V to control lighting devices. This used to be a very common control method, but earlier there was no widely accepted standard. It has been superceded in parts of the entertainment lighting market by DMX512 and other digital protocols, but a significant portion of the entertainment industry still makes, sells, and uses 0-10V equipment. It is particularly important in the custom market on projects where specifiers want a simple and easy to trouble-shoot protocol. The signal intepretation is the following: Zero volts is considered the "off" condition. When dimmer receives zero volt input signal, it should turn it's output off (there can be some idle voltage if defined on dimmer itself). In case of motion control, the receiver should position itself at one extreme. In case of speed or rate control, the receiver should set speed to minimum or stopped. In case of audio volume zero voltage could be off or maximum attenuation. Note that when a console or other sending device is powered down or disconnected, it sends zero voltage to all receivers. The "off" condition of a receiver should always be a safe condition. Ten volts is considered "on" condition. When a controller is sending a level od 100% or "full", it should place ten volts on the output. When dimmer receives 10V input, it should tur its output fully on (can be less than full line voltage if maximum is defined so on dimmer). In the case of motion control, the receiver should position itself at the opposite position form "off". A rate or speed control should go to it's fastest speed. The 0 to 10V control is intended to be linear. The output of a receiver should be "half" when it receives 5V control voltage. A dimmer at half may bring lamp to half intensity or output ar half it's maximum voltage (in productions the response curve form control voltage to lamp intensity should be defined). The output of the controller shall be a steady DC voltage. When the control level is constant, the output shall not change by more than +/-20mV. The output shall vary between 0 and 10 volts. Zero voltage represents off condition and then volts is full on. The output voltage shall never be less than -0.5V and nor more than +10.50V. Output voltage levels are to be measured with a load of 20 kohm. Passive controllers, with unbuffered outputs, shall use potentiometers with a resistance value of 10K ohms or less (=output impedance of 5 kohms or less). Active controllers with buffered outputs must have an output impedance of 100 ohms or less and be capable of continuously sourcing at least 2.0 milliamperes. Controllers and output devices shall be provided with a blocking diode (or similar circuit) such that each output presents an open circuit to any source voltage of more than itself. The blocking diodes allow multiple controllers or outputs to be paralled to control the same dimmers or receivers on a "highest takes precedence" basis. It is recommended that controllers and output devices have current limiting on all outputs such that they are not damaged by short circuits to signal common. The control signal and all control connector pins shall be isolated from AC mains (line and neutral). It is encouraged that the control signa be isolated from earth ground. Those specifications above generally apply to the new devices. Please note that there is a lot of old 0-10V devices that might not meet all of those specifications. There is a one variation connonly used at variation normal 0-10V control approach, this is used widely for controlling fluorescent lighting dimming ballasts. The dimmable fluorescent light ballasts are typically controlled through 1-10V voltage control system. Many ballasts supply a low voltage (12-15V typically max) limited current (typically 0.5-0.6 mA) to their control outputs, so that the dimming can be controlled with just a potentiometer (1.8 kohm gives around 10V and 200 ohms gives 1 volt to the ballast). The definition of 1-10V ballast controlling method is included to IEC 60929 standard. In this system one controller can control up to 50 ballasts. Active control voltage range is 1-10V (voltages in 0-10V range are allowed). In this system every ballast is a current source that feeds 0.2-1 mA current to the line (0.3 mA typical). The controller is a current sink that sinks current so that the voltage on the line drops to ne wanted control voltage level. The controller current sink must be able to sink up to 100 mA at 1V output and up to 50 mA at 10V output to be able to control many ballasts (up to 50). The controller must be able to work with as low as 0.2 mA current to work reliably with only one ballast connected. The standard is only designed for lamp dimming level controlling (no special on/off controlling).
General information
Connector pinout collections
Connector pinouts0 to 10V cables can be almost any type of conductor or cable. There are large set of connectors used by different equipment for this. The ESTA 0-10V standard says that dimmers or receiving devices shall use connectors with male contacts (pins). Controllers or sending devices shall use connectors with female contacts (sockets). If suitable connectors are not available in both sexes, the same connector may be used on dimmers and controllers (typical 8-pin DIN). Pin-out of all control connectors shall be labeled adjacent to connector showing all pin assignments. It is recommended, that where possible, pin numbers should equal channel number and highest pin number should be used as signal common. Most connectors used are wired pretty much in this line.Some equipment can have low voltage power (less than 30V) supply pins on the same connector.
DC light control related circuits
Ethernet in light controllingEthernet is the most commonly used standard computer communications protocol used in local area networks. Moving lights, modern dimmers and lighting control desks all contain computers, so it coming to wide use for lighting control as well. Ethernet is capable of controlling massive numbers of lights, but at the moment Ethernet light controlling suffers from slightly lower reliability and less standardization than traditional DMX-512 interface. Ethernet using twisted pair wiring is coming to the lighting industry controlling, but the manufacturers have not yet have agreed on a common Ethernet protocol. Current Ethernet standards define the pyical network and addressing, but there are no standard for the format and content of the packets to be used for lighting equipment controlling. Nowadays there are some implementations of Ethernet based light controlling but those are proprietary solutions which are not compatible with each other. Some implementations run on Ethernet level and need their own Ethernet segments, while some other rely on using TCP/IP protocol running on top of the Ethernet. Generally speaking Ethernet cabling is cheaper than currently used cabling systems and it can replace many different control cabling, so in not-too-distant future Ethernet an take an important role in theatrical and lighting control technology. There are nowadays several protocols cometing on the Ethernet lighting control. ACN (or the ANSI BSR E1.17 standard) is the next generation control protocol that is under development by ESTA (Entertainment Services and Technology Association). It will operate using Ethernet and is intended partly to address the limitations of DMX512. This standard is under development at the moment. Art-Net is a protocol used, for example, for things like theaters to transport lighting data over Ethernet. The protocol is designed by Artistic Licence and put into the public domain. Its purpose is to allow transfer of large amounts of DMX512 data over a wide area using standard networking technology.
MIDI Show ControlMIDI is short for musical Instruments digital Interface. It was originally used to link keyboards and music syntetizers. MIDI is now used for linking lighting boards together, controlling dimmers and running shows. MIDI is event based, that is messages are sent to indicate what must changed, and the value to which it must be changed, rather than constantly updating the receiver. The data rate of MIDI is 31.5 kBaud. MIDI interface is based around opto-isolated current loops. A typical application for MIDI in show lighing is to leave the "controller" as a device that stores sets ofdimmer levels (called a "scene" memory or "preset") and you could selectwhich scene to play from any MIDI device. This would imitate the functionality found on a lot of lighting boards (some advanced boards have even MIDI interfaces). Depending on the application the controlling can be done using MIDI Show Control messages (standard for control messages being passed over MIDI) or justsimple note-on note-off messages with different notes triggeringdifference memories on your controller. MIDI can be used to control the dimmers directly. There are a couple of MIDI dimmer packs out there. Technically MIDI a lot easier protocol to work with than DMX, since the bit-rate is so much less.But the use of MIDI is not really the standard for lighting control, which means your options will be limited if you plan to use MIDI for this (you are limited to few manufacturers, and changing to use devices from other manufacturers later can be hard).
RS-232 lighting controlRS-232 is not widely used for controlling lighting instruments in the lighting industry. There are some disco effect (quite rare) that can take in RS-232 signal. In some lighting applications controlling lighting through RS-232 interface could be useful. Usually this is accomplishes by using a special converter box which takes in RS-232 signal and outputs suitable control signal that the lighting instruments can use. There is a lot of entertainment kit designed to takeRS-232. Any company which is trying to get out of straight theatre ofdiscos will have such kit, because it allows them to be used in museums,commercial developments, shopping malls and restaurants with boutiquediscos run off central time cues. RS-232 systems generally allow the signal source to generate a one word string (or sometimes longer control word). The RS-232 listening devices are simplyprogrammed to respond to that string. It is very basic really, but veryeffective because it allows you to interface anything - all device suppliers will give you a documentation or library of commands for their kit (different manufacturers use different commands). In many special applications which combine technologies from different technology areas then RS-232 is usually the only sensible interface to use. It is universal for interfacingAV/Lighting/Comms/Networking/Blinds/Doors/HVAC and everything else in abuilding management systems (BMS). There are variousprotocols by specific BMS manufacturers, but ALL of them have RS-232modules. Why? It is the universal protocol for such equipment.
Other professional lighting control interfaces
Here is some description of some lighting protocols that have been once widely used but not used much nowadays. The descriptions are mainly based on article LIGHTING CONTROL PROTOCOLS that appeared in ESTA's Protocol, Fall 2000 issue (it's on-line reprint). Proprietary multiplex protocols are the manufacturer-specific console-to-dimmer data communication schemes that preceded establishment of the universal DMX512 standard. Most of these protocols came into being in the early 1980s, which, for better or worse, coincided with good times in the entertainment and architectural lighting markets. Dimmer-per-circuit systems became the industry standard. Everyone was using microprocessors. A lot of consoles and dimmers were sold! Nearly 20 years later, most of those consoles are gone, but the vast majority of dimmer racks and packs are still in service, and will probably remain so for another decade or more. But keeping those dimmers working means that, when a new control console is purchased, its DMX output must be translated to whatever the dimmers' native language is. Strand's extremely popular Light Palette consoles and CD80 dimmers first appeared in 1979, and with them came a new multiplexed analog control scheme that would later evolve into USITT AMX192. It was soon incorporated into Mantrix consoles and Environ architectural dimmers; in fact, virtually every North American Strand product designed until very recently included at least one AMX port. AMX192 is virtually non-existent outside of the U.S. and Canada. Strand's R&D group in the U.K. devised a somewhat different analog mux protocol they designated D54 (an internal standards number) to work with their Galaxy and Gemini control desks. D54 never made inroads into North America, but it ended up everywhere else in the world. D54 runs over 2 wires, a signal conductor that carries both the dimmer levels and the clock signal, and signal common. it uses only 3-pin XLRs and one pinout: common on pin 1, no connect on pin 2 and signal on pin 3. 384 dimmers are supported. D54 uses 0-5 volt dimmer levels. Possibly the earliest digital lighting control protocol to appear was from Avab of Gotheberg, Sweden. In the late 1970s, the company developed an asynchronous digital output card for their 2000 series console (later known as the Viking), which could communicate with a remote analog demultiplexer. In 1980 the technology was applied to the DD-I digital dimmers. In the early 1980's most of Avab's equipment utilized this protocol. Avab protocol runs at 153.6 Kbaud and 8-bit resolution. FFh is reserved as a frame header, so the maximum signal level is FEh (decimal 254). Early control consoles sent 128 dimmers per packet, later increased to 240. The Expert series consoles were capable of sending 252 dimmer levels. RS422 was used for the data link. All consoles sold in North America were modified to incorporate a "console present" output, which, by changing from a high to a low state, signals the dimmer racks that the console is sending valid dimmer data. The dimmer rack data connection used either a DB25 or circular connector with the following pinout: common on pin 7, data+ on pin 8, data- on pin 9, and console present on pin 12. CMX (sometimes called C-156) traces its beginnings to an innovative control console called Channel Track that Colortran unveiled in 1979. A digital data stream, sent from the CPU over a coaxial cable, was decoded by a local D/A converter into individual 0-10 volt analog levels. These products utilized RS422 differential data transmission for remote D/A's or direct control of dimmers. CMX receivers included a 108-channel D/A card produced in the early to mid-1980s and the popular D192 high-density dimmer rack introduced in 1985. Virtually all control and dimmer products sold by Colortran were user-configurable for either CMX or DMX operation by 1989. Two slightly different transmission speeds were used: 156.25 Kbaud for early systems and 153.6 Kbaud from about 1985 on. There's not enough difference between the two rates to matter, so a controller running at either speed will work with any dimmer rack. CMX protocol was the prototype for today's DMX512. The only major difference is the data rate, which was increased to 250 Kbaud for DMX. design team designated the first word of the data stream as an identifier for the type of information to follow (now DMX512's start code!). CMX pioneered the familiar 5-pin XLR and pinout later adopted by DMX512: shield/common on pin 1, data- on pin 2, data+ on pin 3. Some products such as Status consoles received their DC power from the dimmer pack on pin 5. Electro Controls entered the digital protocol race in 1983. They introduced ECmux protocol, originally known as "Celebrity Protocol" after the console that it was developed for. The protocol was expanded in 1985 to carry channel/dimmer softpatch information. Strand acquired EC in 1986. By 1992, Strand had stopped production of all EC-designed equipment except a new Premiere architectural control system. ECmux was an asynchronous protocol operating at 187.5 Kbaud and 8-bit resolution. EC employed a single-ended (one wire plus common) transmission line for their data signal, which limited the practical control cable length to 150 feets (50m). ECmux used a 4-pin XLR connector, wired as follows: shield or common on pin 1, data (minus) on pin 2, rack overtemp sense on pin 3, and no connection on pin 4. ECmux can carry level data for 512 dimmers in one continuous packet. All protocol versions reserved FFh for a start code, so the maximum value that a channel can reach is FEh (decimal 254). ETC/LMI is a synchronous protocol utilizing two wire pairs. One pair is used for dimmer data and the other carries a sync signal. A 4-pin XLR connector is used for the signal lines, and signal common is ground-referenced at each end of the transmission line. LMI's pinout was data+ on pin 1, data- on pin 2, clock+ on pin 3 and clock- on pin 4. ETC consoles generally swapped the functions on pins 1 and 2. Data rate is 250 Kbaud. The protocol was originally designed to handle 144 dimmers, but ETC expanded its capacity to 1000 or more with the addition of softpatch functionality. Kliegl Bros. introduced their new digital control protocol along with the popular K96 fully digital dimmer rack system and the Command Performance console in 1981. K96 was a powerful protocol that incorporated data compression, high level commands and dimmer talkback features, although these advanced features were generally not used. It also carried softpatch data for storage in the rack processors. K96 runs at 83.3 Kbaud with 7-bit resolution. The protocol handles up to 512 channel levels and provides softpatching for thousands of dimmers. The electrical interface is RS422 with one pair used for control and the other for talkback. The Entertainer console is the only one that used the talkback feature. Entertainer and P-3 consoles had a 7-pin Viking connector with following pinout: pins 1-3 common, pin 4 talkback-, pin 5 talkback+, pin 6 data-. and pin 7 data+. P-4 consoles used a DB9 with common on pins 1 and 2, data+ on pin 3, and data- on pin 4. Wall plates generally had a 5-pin XLR where the shield was on pin 3, the data pair on pins 1 and 2, and talkback on pins 4 and 5. Teatronics introduced their own analog multiplex protocol in 1981 (used in Director and Producer series lighting consoles). The only dimmers that received the Tmux protocol were the first generation of Genesis 6 and 12-packs. Analog was transmitted as a balanced, low impedance signal on a pair of wires, and the synchronizing clock was a high impedance signal on one conductor paired with the signal common. 5-pin XLRs were used: common on pin 1, analog+ on pin 2, clock on pin 3, analog- on pin 4 and no connect on pin 5. LMX-128 is a multiplexed lighting control protocol used mainly by Lightronics. It is an industry standard 128 channels 3 wire multiplex protocol (also known as NSI/Sunn three wire multiplexed protocol). The control interface used 3-pin XLR connectors and normal microphone cables. The control signal pinout is: LMX common on pin 1, console power on pin 2 and multiplex signal on pin 3. The protocol is basically same as Microplex MPX. The data sent through the cable is analogue multiplex signal. The mux control signal is 0-10 volts. Bit Serial Protocol (BSP) is a protocol for transmission of data to lighting devices. It was introduced by Siemens Lighting (now Transtechnik.) at late 1970's for their B40 product line. BSP uses the standard serial transmission via rs422. BSP is asynchronously clocked with 250KBit. The Sender (Master) issues the clock rate via a clock line. Transmission uses the 8N2 schema. The connector has 5 pins assigned with symetric clock and data and gnd. (+clock, -clock, +data, -data, gnd). Transmission is divided into frames of up to 512 bytes. Valid data bytes have values from 1-255. Value 0 is invalid and used to mark a new Frame. A typacal frame is three Frame Start characters (value 0) followed by up to 512 data bytes (value 1-255). IEC 60929 PWM standard is one controlling protocol for controlling electronic lamp interfacing components (other protocols in this standard are 1-10V and DALI). This pulse width modulation (PWM) method uses a signal that has two levels: low level (0-1.5V) and high level (10-24V). When the line is at high level 5% or less of the time the lamp is at highest output level. Lamp is at minimum level when signal is 95% of time at high level. If signal is more than 95% at high level, the lamp is turned off. The response from puse width to ligh level is logarithmic. The pulse time can be at 1-10 ms range. This PWM method is standardized but not widely used as general controlling protocol, but it is quite much used with cold cathode fluorescent lights and LED light source controlling. Most often the PWM signal is generated using a controlling interface converter that is controlled though DMX512 or DALI bus.
Home automation and lighting controlX-10X-10 is a power line carrier protocol that allows compatible devices throughout the home to communicate with each other via the existing 110V wiring in the house. Using X-10 it is possible to control lights and virtually any other electrical device from anywhere in the house with no additional wiring. X10 is a communications "language" that allows compatible products to talk to each other via the existing 110V electrical wiring in the home. X10 devices can be categorized into 3 distinct groups: Transmitters, Receivers and Transmitter/Receivers (2 Way X10 devices). X10 Transmitter devices send a coded low voltage signal that is superimposed over the 110VAC current. Any X10 Receiver device plugged into the household 110V power supply will see this signal. However, the Receivers will only respond when it sees a signal that has its address. Up to 256 different addresses are available. If you want more than one device to respond to the same signal, simply set them to the same addresses. X-10 operates at 120 kHz frequency range. X-10 adds short bursts of 120 kHz carrier after each mains zero crossing to send data. Each data bit takes two zero crossings, so the data rate is 60 bps. This is enough for slow control applications.
DALIThe drive for Energy Conservation and Intelligent Building Automation has led to the development of the DALI standard for control of Lighting Networks, especially those involving Fluorescent Ballasts. Backed by the major Lighting manufacturers in the world, the DALI interface allows for low cost control of large networks. DALI (Digital Addressable Lighting Interface) is a quite new industry standard to lighting control systems. DALI is supported by the main lamp and ballast manufacturers in Europe (Helvar, Osram Philips, and Tridonic). Backed by the major lighting manufacturers in the world, the DALI interface allows for low cost control of large networks. The DALI system mentioned as extension to IEC60929 standard. DALI is a dedicated communication interface for the control of lighting systems at local room level. It has been developed specifically for optimum lighting control, both in Local Room Control applications and when interfacing with Building Management Systems. The DALI protocol is exclusively designed for lighting and aims at filling the gap between the standard 1-10 V analog control interface and the more complex universal bus systems, which are too advanced for many applications. DALI interface is suitable for mid-size rooms and stand-alone systems. DALI system is the combination of ballast switching and dimming via the control wire with ballast addressing. The key feature of DALI is individual ballast addressability, which enables up to 64 different luminaires on the same control circuit to be switched and controlled independently. The luminaires on a single circuit can be combined in up to 16 freely definable groups, in which individual light can be assigned to one or more groups. Programmablity allows installations to be reconfigured without the need for costly wiring changes. Wiring using DALI is very simple: all the luminaires in a room are simply connected to the nearest unswitched power supply, as well as to a single control cable from a lighting controller. DALI is the de facto industry standard for the control of lighting systems. The system concept and communication protocol are now accepted as a draft IEC document with preparations for the definitive IEC standard at an advanced stage. DALI operating voltage is 9.5-22.4 V and DALI system current is max. 250 mA (limited on power supplying bus master). In general the control line voltage in a DALI system is normally 16 V (between 22,4 and 9,5 volts) when there is no communication (idle state). DALI bus power is supplied from additional power supplies. The DALI power supply must limit the supply current to max. 250 mA under all circumstances. In practical installations the current is good to limit to a lower level in order to maintain the flexibility of changing the layout and increasing the system at later stages. There is no limitation to having several power supplies on the same DALI control line as long as the current limit is not exceeded and the supply polarity is taken into account. Since the DALI signal varies between 0V and 16V the polarity is important to maintain also with power supply. A typical DALI equipment consumes around 6 mA of current from the bus. Good practice is to allow sufficient margins for the supply current. This will guarantee reliable system functionality under different conditions and also allow the flexibility. DALI data transmission speed is 1200 Baud. Data is transported through one wire pair. The transmission circuit consists mainly of a power transistor switching the bus power on and off. The digital signal becomes low when the voltage level in the DALI system becomes zero. Digital interface in devices is insulated in accordance with EN 60928 (basic insulation). Guidelines for SELV installations do not apply to the DALI signal. The low voltage installation requirements apply. DALI uses standard mains rated cables for electrical installation (supply and control). Supply and control wires can be laid together in one cable or duct. There is no special wiring required with regard to wiring topology (star, series and mixed networking allowed). Maximum cable length of DALI control wires 300 m (for 1.5 mm2). All devices in a DALI system must comply with the following European standards: EN 55015, EN 61547, EN 61000-3-2 and EN 63000-3-3. Some major characteristics of the DALI protocol are (from http://www.freescale.com/files/microcontrollers/doc/ref_manual/DRM004.pdf and http://www.dali-ag.org/c/manual_gb.pdf and http://www.semiconductors.philips.com/acrobat_download/applicationnotes/AN10225_2.pdf ): The DALI communication is serial using two wires for communicating in both directions. The voltage difference between the wires indicates if it is a high or low level. A voltage difference above 9.5 V is a high level and a voltage difference less than 6.5 V is a low level. The master unit communicates with the slave units by setting the level high or low according to the serial protocol. When no communication takes place the master unit keeps the level high. The slave unit responds to the master unit by setting the level high or low. A high level is simply achieved by not interfering with the high level set by the master unit. A low level is obtained by forcing a short circuit across the wires. This is possible to do since the DALI standard states that the current supply for the DALI communication has to be limited to 250 mA. There are a number of parameters stored in each slave unit. These parameters indicate how the lamp should behave in different situations. Messages can be sent over the DALI communication wires to change or check the values. All communication is controlled from a master. Every lamp is connected to a slave unit that is silent until the master requires an answer. The 16-bit data from the master unit consists of an 8-bit address part and an 8-bit command part. Up to 64 slaves can be connected to the same network and each slave can receive an individual address, which is called the short address. There is also the possibility of assigning a slave unit to a group. Up to 16 groups can exist and a slave unit can belong to several groups. A message can also be broadcasted to all slave units. More information on DALI protocol can be found in the document A.C.-Supplied Electronic Ballast for Tubular Fluorescent Lamps, Performance Requirement, Requirements for Controllable Ballasts which can be obtained from IEC. DALI stands for Digital Addressable Lighting Interface and is a protocol set out in the technical standard IEC 60929 under Annex E. AG-DALI is a working group set up by leading manufacturers and institutions in the field of digital lamp/luminaire control to promote DALI technology and applications.
EIB (European Installation Bus)The European Installation Bus (EIB) is an open, comprehensive system which covers all aspects of Building Automation. It is managed by the neutral EIB Association. The European Installation Bus is designed as a management system in the field of electrical installation for load switching, environmental control and security, for different types of buildings. The InstallationBus can be installed in large buildings such as business premises, schools, hospitals, factoriesand administration premises as well as in domestic residences. Its purpose is to ensure themonitoring and control of functions and processes such as lighting, window blinds, heating,ventilation, air-conditioning, load management, signaling, monitoring and alarms. The EIB is an intelligent building control system which is able to control, regulate, measure, switch, service and monitor. Its basis is a communications bus which lies in parallel with the 230V mains network. EIB is a fully peer-to-peer network, which accommodates up to 65?536 devices. The logical topology allows 256 devices on one line. The EIB system allows the bus devices to draw their power supply from the communication medium, like Twisted Pair or Powerline (230 V mains). The EIB protocol is today supported by several media, like Twisted Pair, Powerline, RadioFrequency and Infra-Red. It is of course always possible to connect gateways to other media. Possible media types: |
|
Home
|
Electronics
|
Computers
|
Machines
|
Sound
|
disclaimer
|
