Control/Dimming Help going from CMX to DMX

[pakimunda101]

Hi Guys,
i am a student in socal and work part time at this events center down here that is filled with over 25 years or older technology. We currently have a colortran system in house that we use to stage light and other ambient lighting. It is on the old CMX system and i am looking to getting the signal converted to DMX. I have found these CMX to DMX converter but they introduce a delay in the signal and for the shows we do, we need something more permanent into the system itself. I have heard of people saying that you can switch the chip and a few other components within the dimmer pack to make it from a CMX to DMX. is that true? and if so what you guys think? ne suggestions on where i could call to get a quote and stuff? thanks and much appreciated

 

[Grog12]

I can honestly say I've never heard of CMX. Are you talking about an AMX system? If so there's quite a few ways to convert over.

 

[Clifford]

CMX is a Finnish rock band.

AMX is a lighting protocol. I didn't know anyone still used it. I think ETC has (or had) something for AMX to DMX. In the 80's, people were using Strand AMX boards with ETC DMX Dimmers and they needed a translation. That's the only thing I've ever heard of/seen.

 

[Sean]

CMX is a Finnish rock band.

AMX is a lighting protocol. I didn't know anyone still used it. I think ETC has (or had) something for AMX to DMX. In the 80's, people were using Strand AMX boards with ETC DMX Dimmers and they needed a translation. That's the only thing I've ever heard of/seen.

CMX is essentially the predecessor of DMX. It's slower, but very similar otherwise.

It is/was Colortran's proprietary protocol, and a lesser-used contemporary of AMX-192.

Also, I believe you have it reversed. The Strand CD-80s (AMX) were widely used (both rentals and install). After the introduction and adoption of DMX there was still the need to control the (older) CD-80 dimmers with newer DMX-capable boards.

There is a great book, The Speed of Light by Linda Essig that you should read.


In response to the OP, I'd check with Colortran itself (now owned by Leviton) and/or Doug Fleenor Design Doug Fleenor Design - Home Page - Ph & FAX 805-481-9599


--Sean

 

[SHARYNF]

the difference between cmx and dmx is predominately the speed.

From http://www.pathwayconnect.com/content/view/12/26/ :

CMX
History - 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. The protocol appeared in its present form in later designs, such as the Patchman, Dimension 5 and Prestige series consoles. 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. As many people in the industry are aware, 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. Interestingly, Colortran's design team foresaw the need for the protocol to talk to more than just dimmers, so they designated the first word of the data stream as an identifier for the type of information to follow (now DMX512's start code!).



Details - 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 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.



Interfacing Hints -- Problems may be encountered if you try to read and convert the CMX output from a Patchman console. This unit sent even parity instead of a second stop bit, which will confuse many receivers. Caution: before connecting new control equipment to an older Colortran dimmer, first ensure that no power supply voltages are present on pins 4 or 5.

It should be able to be upgraded. I'd contact NSI/Leviton OR give Doug Fleenor an email dfleenor at dfd dot com . Doug is a wealth of information.

Sharyn

 

[SteveB]

In the event that you have Colortran D192 dimmers, the control electronic module can can be easily and relatively cheaply converted to DMX.

I would contact Steve Short at Litetrol Service in Hicksville, NY. Litetrol has most of the older C-Tran dimmer and console parts that NSI didn't move from SoCal to Oregon ?, way back when NSI brought up C-Tran. Steve can do this chip conversion. 1 800 LITE-TROL

Also check the age and model number of the CEM's as I think some can automatically read DMX or CMX. Just a vague memory there...

Steve B.

 

[lieperjp]

We have this little baby from Leviton:

Product Details

Our system is CMX, installed 1997. Whoever spec'd the system was an idiot.

I don't notice a delay, and I have it set up to go from board to DMX splitter to Converter to Dimmers. It's rack mountable (very small.) The only thing I do notice that there is no noticeable light output from the lights until the board is at 18%... but I think that's the dimmers, not the converter. Leviton also has other versions, just search the site.

I don't know how much it cost, I think we got it for free with our Innovator, but I'm not sure, I wasn't around when they got it.

 

[ruinexplorer]

Our system is CMX, installed 1997. Whoever spec'd the system was an idiot.

I don't notice a delay, and I have it set up to go from board to DMX splitter to Converter to Dimmers. It's rack mountable (very small.) The only thing I do notice that there is no noticeable light output from the lights until the board is at 18%... but I think that's the dimmers, not the converter. Leviton also has other versions, just search the site.

I whole heartedly agree. I don't know why there is still anyone using the old multiplex type of protocols, but there are still quite a few who do (NSI/Leviton, Lightronics, etc.). You might want to check out Johnson Systems Inc. for making your system work. I've talked to them at LDI and have good recomendations for their work from some of Barbizon's installers.

 

[bdkdesigns]

You might want to check out Johnson Systems Inc. for making your system work. I've talked to them at LDI and have good recomendations for their work from some of Barbizon's installers.

We just installed ours the other day. They seemed to work great on the initial tests. The other bonus is how easy those things are to install. I'd say we spent the first 45 minutes looking at the rack and reading the directions to make sure we had it right. Then it only took about 10 minutes tops to install each one. All that's left to do now is hook up the DMX but we won't have that line for awhile yet.

 

[STEVETERRY]

Hi Guys,
i am a student in socal and work part time at this events center down here that is filled with over 25 years or older technology. We currently have a colortran system in house that we use to stage light and other ambient lighting. It is on the old CMX system and i am looking to getting the signal converted to DMX. I have found these CMX to DMX converter but they introduce a delay in the signal and for the shows we do, we need something more permanent into the system itself. I have heard of people saying that you can switch the chip and a few other components within the dimmer pack to make it from a CMX to DMX. is that true? and if so what you guys think? ne suggestions on where i could call to get a quote and stuff? thanks and much appreciated

The simple conversion from CMX to DMX involves:
1. The installation of a 4 MHz crystal to allow the UART to run at 250 kbps.
2. Changing one resistor value

Steve Short at Lite-trol should be able to help.

BTW, another post mentioned that CMX anticipated/supported alternate start codes. This is not true--alternate start codes were introduced during the creation of the DMX512 standard in 1986 by a proposal from Matt Deakin, then of Celco. Colortran gear always had a zero start byte, but never considered alternate start codes. Colortran dimmer control modules were pure hardware implementations with no processor--just a TTL state machine connected to a UART and a ramp-and-comparator firing scheme.

Also, there is some mythology about the actual bit rate of CMX. It has always been 153.6 kbps.

Finally, people's confusion over the name CMX is understandable. The was no "CMX" until after 1986 when DMX512 was introduced. Then the Colortran marketing department created "CMX" instead of the prior "Colortran Protocol".

ST

 

[someguy98457]

Do you know which resistor needs changing? and to what value? I'm on the control modules for the portable packs.

 

[AhClem]

Is there any documentation showing the changes mentioned (resistor and crystal) on a Colortran ENR Series 24 dimmer rack?