Building DMX Cables
- Thread starterJoeML
- Start date
JD
Well-Known Member
Odd thing is that some of the better "2 pair" cable is actually not 2 pair, but one big twisted quad! If you are only using it for standard DMX, it does not really matter. However, if you intent to do some of that non-compliant stuff, like send a second universe down the other pair, you want to inspect a sample of the cable and see that there truly are two separate 2 wire pairs. Ideally, I like to see separate shields around each pair, but that's just me! The fact that DMX works great using CAT5 cable (in non-flex applications) which is not shielded at all, proves that is not a requirement.
Whatever you do, suppress the urge to use the second pair to double up the conductors on pins 2 & 3. My own take is to solder all unused conductors to pin one as that leaves no "strays" that may bite you later. The other alternative is to cap the unused wires with heat-shrink like Derek said.
Whatever you do, suppress the urge to use the second pair to double up the conductors on pins 2 & 3. My own take is to solder all unused conductors to pin one as that leaves no "strays" that may bite you later. The other alternative is to cap the unused wires with heat-shrink like Derek said.
Ok, so I could either get the Accu-Cable @ $104/300', Gepco DS601<- Not listed as DMX @ $95 or maybe the MAXPRO DMX500MP @ $100 stuff.
So im thinking any DMX cable with shield and twisted are the same, like an a HDMI cable. You can buy the cheapest or the most expensive name brand, but still get the same results.
And thanks for all the help!
So im thinking any DMX cable with shield and twisted are the same, like an a HDMI cable. You can buy the cheapest or the most expensive name brand, but still get the same results.
And thanks for all the help!
DuckJordan
Touring IATSE Member
Kind of, Although I have noticed with the cheaper cable that it isn't nearly as durable as some others. I've found that over time as wrapping and unwrapping and just overall use will slowly deteriorate the individual wires as well as the outer jacket.
Ok, i guess i did think about that part of it. Good call!
I hope your overall time frame is at least 5 years? Cause my current cables have lasted almost 10 years now! Although I do keep them out of way. Put carpet over them instead of tape in walkways, or run them along the walls and clean them with water when muddy.
I hope your overall time frame is at least 5 years? Cause my current cables have lasted almost 10 years now! Although I do keep them out of way. Put carpet over them instead of tape in walkways, or run them along the walls and clean them with water when muddy.
Avoid the Gepco DS601. 26g is too small (not for current, but for mechanical strength, purposes), and you want a braided, not foil, shield for durability.
DuckJordan
Touring IATSE Member
actually the cables that broke or caused problems cause issues in 2 years and was from only about 20 uses, This was at a local College and were the last to be put in first to be pulled out kind of thing. So very, very careful with the cables.
tdrga
Well-Known Member
Rosco/ET IPS dimmer bars and packs use pins 4/5 for talkback. One of the very few actual useful and compliant uses of pins 4/5.
They are no longer made by Rosco and ET doesn't exist anymore- I'm not sure if the current Philips/Strand S21 products that are descended from the IPS line still use pins 4/5.
-Todd
Technically, there are no "compliant" uses for pins 4 and 5 according the the DMX standard. They were reserved for future use and that future use was never actually specified. So, technically, any use of pins 4 and 5 is not compliant with the DMX standard, much the same as using an XLR-3 connector is not compliant..
tdrga
Well-Known Member
Actually, the language in the ASNI E1.11 2004 document refers to the secondary data link as "optional"- and it is specified as another EIA-485-A data link. From Annex B of the standard:
"The original and 1990 versions of USITT DMX512 called out an “Optional Second Data Link.” There was no detailed guidance for it use. The majority of legacy systems did not use the second data link at all. Many uses of the second data link have been implemented over the years. While many of these were reasonable, a few uses clearly were not compliant with EIA-485-A. These uses vary in both their electrical requirements and in the data protocol used. One of the purposes of this standard is to regularize the use of the second data link . It is no longer possible to select a single implementation and forbid all others. However, not all historical uses will be allowed to continue."
Earlier versions of the DMX standard did not deal with pins 4/5 and left them as "reserved" but the current DMX-A standard does specify that they must be a data link. So the Rosco/ET products are compliant with the current standard (even if by chance, since they were designed before the DMX-A standard existed).
-Todd
They don't? Entertainment Technology
They better, I love me some Bak Pak dimmers!
tdrga
Well-Known Member
Well, I stand corrected- I didn't realize that ET remained as a distinct division within Philips.
-Todd
I've asked this before and not received a satisfactory response:
What's the difference between an ET Bak Pak and a Strand Light Pack?
I don't know if this is the answer that you are looking for, but a few months back, I purchased a Strand Light Pack on ebay. I did so because the price was to good to pass, and it looked just like the ET Bak Pak, and I also wanted to get my first IGBT dimmer. I pulled an adhesive label from the unit, and underneath it is a ET Bak Pak.
Tom Johnson
