I have 3 test (Tstat7) devices on a simple modbus daisy chain.
At one end is a USB dongle w/ RS485 connections. All wiring seems good.
I have one device (ID=4) that I can communicate with reliably on address=4.
I can communicate with it in position 1, 2, or 3 of my workbench daisy chain modbus network.
The other 2 Tstat7 devices will just timeout, regardless of physical location on the network OR the device ID that I give them via the device menus.
Any assistance would be greatly appreciated. Seems like I am missing something simple.
I’ve tried modifying the device IDs (via the device menu) and have had no luck yet.
And we use an oscilloscope to check RS485 level type problems like swapped A and B lines, swapped 24VAC common and GND amongst devices, that sort of thing:
Thank you, that’s good to know.
However, I think the wiring is OK because I can swap device positions (across the three back plates) and I get consistent communication from the ‘working’ devices, regardless of a position on the daisy chain.
Does that point to a Tstat7 issue?
Is there an easy way to factory reset them?
I’ve scanned from ID 0-255 and there is no sign of them.
The baud rate displayed on the Tstat screen (19200) is consistent with the others and the comms.
We are ready to help out but what I see so far is normal commissionining issues. I strongly urge all
participants listening here, get a scope and data tools like I show above.
