Could someone tell me what cable is required and the pin numbers on the male and female connectors, and is that looking at the cable or non-cable side?
Thanks.
Full Version: Making Dmx Cables
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Well the numbers are printed on either side depending on the make of XLR.
2-core twisted pair 120ohm with overall shield, shield to pin 1, the other 2 wired pin to pin on 2 and 3 at either end. Female one end and male the other.
This is like a balanced mic cable but DMX must not have the shield (pin 1) linked to the plug shell. (mic cables usually will)
2-core twisted pair 120ohm with overall shield, shield to pin 1, the other 2 wired pin to pin on 2 and 3 at either end. Female one end and male the other.
This is like a balanced mic cable but DMX must not have the shield (pin 1) linked to the plug shell. (mic cables usually will)
Some Martin and early lighting has a reversed DMX configuration.
Maybe Superstar DJ can throw some light (pardon the pun) on this as well as the wiring for the 5 plugs.
Maybe Superstar DJ can throw some light (pardon the pun) on this as well as the wiring for the 5 plugs.
Yes, the polarity of the Martin stuff was reversed, ie pin 2 and 3 swapped on the fixture and Martin controllers. The leads are just standard of course as they're not polarity concious!
What you had to watch out for was that if you used a non-Martin controller on a Martin light, or a Martin controller on a non-Martin light, you needed a cross-over adapter to swap pins 2 and 3.
When using 5-pin XLR plugs, you just wire pins 1,2,3 in the same way as a 3-pin XLR, ignoring pins 4 and 5. The same goes if you want a lead with a 5-pin on one end and a 3-pin on the other.
5-Pin plugs are from the original 1980's DMX spec but weren't widely adopted by disco lights (until recently) because of the huge price of 5-pin XLRs compared to 3-pin ones, and the fact that most discos could use spare mic cables for the typically short runs on your average disco rig...they'd work ok.
Some high-end pro fixtures (theatre and TV land) use pins 4 and 5 as another data pair to allow the fixtures to be monitored by a suitable desk, for example errors, internal temperature , lamp life etc...not really for disco use.
Chinese imported XLRs have now made prices largely irrelevant!
What you had to watch out for was that if you used a non-Martin controller on a Martin light, or a Martin controller on a non-Martin light, you needed a cross-over adapter to swap pins 2 and 3.
When using 5-pin XLR plugs, you just wire pins 1,2,3 in the same way as a 3-pin XLR, ignoring pins 4 and 5. The same goes if you want a lead with a 5-pin on one end and a 3-pin on the other.
5-Pin plugs are from the original 1980's DMX spec but weren't widely adopted by disco lights (until recently) because of the huge price of 5-pin XLRs compared to 3-pin ones, and the fact that most discos could use spare mic cables for the typically short runs on your average disco rig...they'd work ok.
Some high-end pro fixtures (theatre and TV land) use pins 4 and 5 as another data pair to allow the fixtures to be monitored by a suitable desk, for example errors, internal temperature , lamp life etc...not really for disco use.
Chinese imported XLRs have now made prices largely irrelevant!
What doe annoy me is that when you buy a lighting kit, ie a pair of scanners etc etc, you get a "free DMX cable" which turns out to be a mic cable with different coloured xlrs on.
Granted i use them and with scanners etc and like SSDJ says over short runs they pose no problem however with my led par cans and par can controller i have a couple of small quirks. The red goes slightly purple and the tap facility packs up after a while.
I have just bought some proper dmx cabling (at least it says professional dmx cable on the insulation) to see if this resolves these small issues.
Dave
Granted i use them and with scanners etc and like SSDJ says over short runs they pose no problem however with my led par cans and par can controller i have a couple of small quirks. The red goes slightly purple and the tap facility packs up after a while.
I have just bought some proper dmx cabling (at least it says professional dmx cable on the insulation) to see if this resolves these small issues.
Dave
In the workshop, I've never had any problem at all using any type of twisted pair cable for DMX, even using some quite complicated chains. DMX uses the RS485 electrical standard which is by nature very robust, it was designed for data transmission around factories etc.
Last summer I was involved in programming a very large lighting rig and we had no end of problems with fixtures doing silly things like flickering slightly when they should have been blacked out, and scanners suddenly resetting on their own etc. I discovered that the installer (who should have known better) had used mic cable; not normally a problem for a disco or pub, but this was an extremely large venue (aircraft hangar sized) with loads of fixtures stretching across large spans indeed.
Although a terminator should always be used, it's important with larger rigs to make sure all the cables are the same, ie not to use a hotch-potch of different cables, since 'impedance mismatches' can cause signal distortion more than simply using 1 type of cable throughout
Mic cable is ok for mobile disco use..its 'mic leads' with earthed XLRs than mustn't be used. If they are, there's a possibility that the shell may contact the earthed truss (eg with LED par cans) which can cause hum-loops, possibly upsetting the DMX. It's rare, but can happen. RS485 is a balanced system like balanced line audio..however that too is not infallible.
In a rival forum to this one, a guy had built an LED parcan rig out of mic cables. It was ok until he tripped over his mains extension lead, this pulled out a mains cable which brushed against the truss and went to earth via the mic screen through his lighting desk. The result was eight LED par cans with eight blown microcontroller chips.
Last summer I was involved in programming a very large lighting rig and we had no end of problems with fixtures doing silly things like flickering slightly when they should have been blacked out, and scanners suddenly resetting on their own etc. I discovered that the installer (who should have known better) had used mic cable; not normally a problem for a disco or pub, but this was an extremely large venue (aircraft hangar sized) with loads of fixtures stretching across large spans indeed.
Although a terminator should always be used, it's important with larger rigs to make sure all the cables are the same, ie not to use a hotch-potch of different cables, since 'impedance mismatches' can cause signal distortion more than simply using 1 type of cable throughout
Mic cable is ok for mobile disco use..its 'mic leads' with earthed XLRs than mustn't be used. If they are, there's a possibility that the shell may contact the earthed truss (eg with LED par cans) which can cause hum-loops, possibly upsetting the DMX. It's rare, but can happen. RS485 is a balanced system like balanced line audio..however that too is not infallible.
In a rival forum to this one, a guy had built an LED parcan rig out of mic cables. It was ok until he tripped over his mains extension lead, this pulled out a mains cable which brushed against the truss and went to earth via the mic screen through his lighting desk. The result was eight LED par cans with eight blown microcontroller chips.
QUOTE(superstardeejay @ May 15 2010, 09:32 PM) 
In the workshop, I've never had any problem at all using any type of twisted pair cable for DMX, even using some quite complicated chains. DMX uses the RS485 electrical standard which is by nature very robust, it was designed for data transmission around factories etc.
Last summer I was involved in programming a very large lighting rig and we had no end of problems with fixtures doing silly things like flickering slightly when they should have been blacked out, and scanners suddenly resetting on their own etc. I discovered that the installer (who should have known better) had used mic cable; not normally a problem for a disco or pub, but this was an extremely large venue (aircraft hangar sized) with loads of fixtures stretching across large spans indeed.
Although a terminator should always be used, it's important with larger rigs to make sure all the cables are the same, ie not to use a hotch-potch of different cables, since 'impedance mismatches' can cause signal distortion more than simply using 1 type of cable throughout
Mic cable is ok for mobile disco use..its 'mic leads' with earthed XLRs than mustn't be used. If they are, there's a possibility that the shell may contact the earthed truss (eg with LED par cans) which can cause hum-loops, possibly upsetting the DMX. It's rare, but can happen. RS485 is a balanced system like balanced line audio..however that too is not infallible.
In a rival forum to this one, a guy had built an LED parcan rig out of mic cables. It was ok until he tripped over his mains extension lead, this pulled out a mains cable which brushed against the truss and went to earth via the mic screen through his lighting desk. The result was eight LED par cans with eight blown microcontroller chips.
Im going to go through all my cables now as i need to do some maintenance/alterations to my pre wired light bar anyway and check them all out.
Thanks again SSDJ
Dave
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