Viewstat Communications

Scottpulman

Hey guys
Need some help with a ViewStat system that has suddenly stopped communicating.
I have 2 Viewstats connected to a Slave Axcent 3 via a distro board.
This system used to work, suddenly stopped, now I am trying to figure out why. To make it even more fun, I did not do this job originally, the original company has gone out of business so I am cleaning up... so to speak.

Anyway. I have communication, well I get responses, however they are not what I am expecting to receive. ( check out the attached screencapture )

I have swapped ports on the Axcent 3, I have tried an NI-700, I have remade the cable ( they were using those *#@Q*T#@$ cat5e to serial adaptors.... ) still nothing.

To me it seems like some sort of baud rate issue, but I can't figure out why. I have verified that the port is set to 9600,N,8,1 and 485 is off, but I still get these random responses.

Has anyone out there seen anything like this before?
Any ideas?

ericmedley

Scottpulman wrote: »

Hey guys
Need some help with a ViewStat system that has suddenly stopped communicating.
I have 2 Viewstats connected to a Slave Axcent 3 via a distro board.
This system used to work, suddenly stopped, now I am trying to figure out why. To make it even more fun, I did not do this job originally, the original company has gone out of business so I am cleaning up... so to speak.

Anyway. I have communication, well I get responses, however they are not what I am expecting to receive. ( check out the attached screencapture )

I have swapped ports on the Axcent 3, I have tried an NI-700, I have remade the cable ( they were using those *#@Q*T#@$ cat5e to serial adaptors.... ) still nothing.

To me it seems like some sort of baud rate issue, but I can't figure out why. I have verified that the port is set to 9600,N,8,1 and 485 is off, but I still get these random responses.

Has anyone out there seen anything like this before?
Any ideas?

I don't think the baud rate is supposed to be 9600. I'm not at my desk right now. But, i thinks its something like 38400 or something. Either way, verify the manual for a vewstat/aprilaire 8870.

e

vining

From the manual:

Network communication is non-isolated, full duplex RS-485 using 4 + I wires. The' A ' tenninals are the transmit
pair while the 'B' terminalsa re the receivep air. This nomenclatureu sest he host computera s the reference,s o
transmit refers to the lines on which the host transmits data to the thennostat while receive refers to the lines on
which the host receivesd ataf rom the thennostat. The baudr ate is selectableb etween 9600 and 19200
.....
To maximize communication speed consider the following:
1. Communicate at 19200 baud
2. Do not skip addresseso n the thermostatn etwork unlessa bsolutelyn ecessary.
3. Set dte "Number of Thermostatso n the Network" to the highesta ddressedth ermostat. If you have only six
thermostatsa ddresst hem 1 through 6 and set the highesta ddressto six.
4. Only turn on the necessaryc hangeo f statev ariables( COS - refer to the commandd escriptions).
5. Ifperforming basic HV AC functionst hat utilize the StatNetc ommands et, and a responseto the commandi s
desired, send commands explicitly when possible. This way, you will be able to send commands widt no more
than 330 millisecondss eparatingth em, 100m illisecondsi f commandsa ren't sentt o dte samet hermostat
consecutively.
6. Unlessa responseis required.w hen sendinga large nUDlbeor f commands,s ett he CommandR esponseto Quiet
or Silent. If responsesa re needed,i t may be fastert o explicitly query eacht hermostato n the network

Scottpulman

VAV

Where did you find that? What manual. The one that I am looking at VST.OperationalReferenceGuide.pdf has the following only talks about RS422, never R2485..... hell even the AMX module ( non duet of course ) is the 'Viewstat422_Comm' module.

Im not putting it past, i think that we have all found conflicting documentation before, just want to get my ducks in a row.

Can you send me a copy of that manual?

vining

My files too big to upload here. Got an email?

I've always used the 422 com module too. That info was form the AprilAire8870_Programming.pdf and I beleive it's the only programming reference they published.

TurnipTruck

What is wrong with the messages?

Most every problem I've seen with an 8870 network stems from one or more stats failing, screwing up the whole buss.