On February 18, 2010 at 01:18, ejfiii said...
Everything ever said or published from Crestron about using cat5 said to use a single pair for x and y so the data is on a single twisted pair. This is Crestron 101.
This has nothing to do with crestron selling wire and everything to do with answering the question so people use cat5 correctly. I have used cat5 for cresnet correctly for years too but know better than to do so the way you have described.
I'm glad doing it wrong has worked for you but please don't encourage others to do things the wrong way.
It's not only Crestron 101 but engineering 101. You can use contact closure wire to carry data and it might work. Cresnet is robust protocol but data is still data. By splitting the pairs you are defeating the engineering design of the wire and making the data the wire is carrying susceptible to corruption. There are nominal twists between each pair of wires but the real benefit of CAT 5 is twist ratio of each pair. Mr. McDonald would not--I hope--terminate a RJ-45 for data where pin 1 was green/white pin 2 was blue, pin3 was orange/white pin4 was green, pin 5 was orange, pin 6 was green, pins 7+8 brown.
Mr. McDonald's response is the same as a company for whom I once programmed. They also used CAT5 and split there pairs. I warned them that this was bad practice but they responded that they never had issues. They did on that job, till they redid every connection on that job correctly.
Anything may work, and splitting pairs will work particularly if the data load is small. Category5/6 wire depends on the twist ratio between each pair to reduce induction and maintain data integrity. By splitting the pair you are relying on the much smaller twist ratio among each pair. But you are taking a very big chance that data will not become corrupted and you system fail to work because you've used the wire in ways in which it was not intended.
Yes, this can work. You can also use CAT5 for video without a baulin and it can work. You can always misuse a wire and still have a working system. I've used contact closure wire with no twist or shield for controlling Grafik Eyes. I had no choice. A while back, in a thread about what wire to use for component video, our friend from Texas suggested that certain RF coaxial cables had the specifications to carry component video over moderate distance. On an other board, someone suggested that you could use 12v power for equipment that required 24v, with the problem of added heat.
One of the main reasons I was told that Crestron stopped supporting CAT5/6 wiring is that too many idiot dealers were not performing voltage drop calculations and running CAT 5 1000 ft with equipment that required 75w of power. The system failed. When faced with repeated stupidity, manufacturers take the path of least resistance. Either they design a product the dealer cannot screw up or they stop supporting equipment not installed correctly to their specification.
Don't split pairs on a CAT5/6 wire if you are carrying data.
Alan
