-klb- Posted December 3, 2012 Posted December 3, 2012 Yesterday we found that a string of 21 controllers was not behaving properly. Thankfully, nothing was yet plugged into the 1st 18 controllers, so they were bypassed, and the rest worked just fine. Today I started with repeating the same steps performed yesterday. Basically the first controller you plugged into was fine, but ones after that would intermittently start blinking. Replacing the cable between the second controller, which had a solid status and the third which blinks intermittently appeared to help, but was not the solution. Eventually I went about half way down the line, and found everything stable. Working back up, I found one that was the problem when included in eitherdirection. I powered it off, and all was well. So the next step was to replace the com chip and power it up. Works fine now.
LOR Staff Posted December 3, 2012 Posted December 3, 2012 RS485 communication can be weird some times. I'm adding your experience to my knowledge
Max-Paul Posted December 4, 2012 Posted December 4, 2012 klb, so the fix was the comm chip? Seen something like this once before. It was an Athena X16 temperature controller on a large process over. One of 6 on that network.A Comm chip is an Integrated Circuit That translate a 0-5 volt signal to a Two wire and ground signal known as A & B. As I remember it A is 0 - +12V and B is -12 to 0V signal. 0V in equals 0V out. And 5V in is +12 and -12 out on the two wires. And you got to have that ground also (ask me how I know) for reference. A&B are on pins 4&5. And the ground is either pin 3 or 6. So you got to have these 4 wires wired properly or you have all kinds of problems. Ya back to those X16 controllers at work. I found that you have to have the A going to A and B going to B or it would not communicate at all for us.So, it appears that klb's comm chip failed to receive or transmit properly. The amps in the chip could not turn on, or stay stuck on. Stuck on, can keep the line high or minus low blocking transmissions on the wire.
GS Posted December 4, 2012 Posted December 4, 2012 Thx Max. Any part number and/or recommended distributor for spare com chips?Thanks again.Glenn
Max-Paul Posted December 4, 2012 Posted December 4, 2012 GS number for the comm chip should be right on the chip. Might try digi key or mouser for spares.
-klb- Posted December 4, 2012 Author Posted December 4, 2012 Once I swapped the chip with one from a spare controller, all is well. I even had the exact same cables as before on that box. Somewhere I have a few spares ordered as direct replacement parts for those on the kit inventory list. I'll put one in the spare and test eventually. Especially as I have about 4 other spare controllers waiting for me to repair.
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