Viewstat Text Messaging Trouble
TurnipTruck
Posts: 1,485
Greetings,
I have been playing around with the text messaging functionality of the Viewstats.
It seems that when a viewstat has a message within one of its four "permanent message" banks, the stats sporadicially re-initialize themselves, often at Netlinx boot-up.
Has anyone had Viewstat re-initialization troubles related to text message windows or other things?
Thanks.
I have been playing around with the text messaging functionality of the Viewstats.
It seems that when a viewstat has a message within one of its four "permanent message" banks, the stats sporadicially re-initialize themselves, often at Netlinx boot-up.
Has anyone had Viewstat re-initialization troubles related to text message windows or other things?
Thanks.
0
Comments
A couple things I would try:
1. Make sure the all the stats are programmed with the actual maximum number of stats in the system. If you left it at the default and don't have that many, it does delay communications as the buss waits for all of them to report in.
2. Put a CHARD command into your port, something like 5 ms, so individual characters go out slower.
3. Make sure your text messages are paced out a bit, not streaming one after another with no pause. Give the stats a second or so to "catch up."
But don't rule out there isn't an unrelated problem coincidental to your messaging. They reset with any kind of issue. I've seen them go into reset cycles when the furnace had a wiring problem and was causing a ground potential differential with the comm circuits (the output terminals are not 100% isolated internally .. really bad engineering decision which I have expressed to them many times). I've also seen bad disty panels cause reset cycles, and sometimes one bad stat can make the others wig out.
These stats are solid enough then they are working properly, but sometimes getting there is a real headache.
I will put in the character delay.
I am queing all command I send to the stats by 4 seconds per command.
I am powering the stats on their own dedicated 24VAC transformer, not from the HVAC equipment. Therefore, the communication circuit is ground-isolated from the communication electronics unless the stat grounds one of, or somewhat de-balances the R and C terminals used to bring in stat power.
The text messaging is a nice feature. I hope I can keep it working reliably.
That's exactly my point, it is not ground isolated. There is an internal link between the comm ground and the R/C terminals. Like I said, some sloppy engineering. I know this for a fact because I happened to be watching the comm buss on a Viewstat system (that was likewise powered with it's own 24VAC supply) when the HVAC people powered down the furnace. When they turned the furnace back on, the Viewstats went nuts and I had to shut the whole thing down to get them communicating again. By all rights there control outputs should have complete isolation from the comm buss, but they do not. I called them on this and got a tech to reluctantly admit I was right; not that he could have denied it really, under the circumstances. But he offered no solution. It turned out something was wired wrong at the furnace, but it still shouldn't have affected my comms. We stabilized it by fixing the furnace, but I am far from confident future issues won't cause the same thing. If I do have more problems, I will isolate them myself by adding an external relay to the outputs.