Hello openhab community.
Is there anyone on OH 3.4.3 successfully using the modbus tcp binding with RTU encoding enabled?
My impression is that RTU encoding is not working resp. the parameter rtuEncoded is simply ignored by the binding.
Here’s my setup:
Growatt SPH10000TL3 BH-UP solar inverter with RS-485 (twisted pair) interface connected to
RS-485 to ethernet converter ZLAN 5143D.
Openhab 3.4.3 on raspberyy pi 4b
I’m successfully able to query my devices holding registers e.g. using tools like “Simply Modbus TCP Client”:
When trying to query my devices holding registers using the modbus binding I see the binding is only sending plain modbus TCP request frames and not RTU request frames even though parameter rtuEncoded is set to true in my thing file.
My thing file:
Bridge modbus:tcp:SPH10000 "Modbus SPH10000" [ host="10.0.0.190", port=502, id=1, rtuEncoded=true]
{
Bridge poller Batteriewerte "Modbus Batteriewerte" start=608,length=1,refresh=12000,type="holding",maxTries=1] //start=608, length=1, refresh=12000, type="holding", maxTries=2 ]
{
//Thing data BatterieSOC "SOC" [ readStart="608", readValueType="uint16" ]
}
}
My log showing the plain modbus TCP request frame:
Request being sent:
00 00 00 00 00 06 01 03 02 60 00 01
Validating the request on https://rapidscada.net/modbus/ I found the request sent by the binding is a plain TCP request frame (and not a RTU encoded frame).
The RTU encoded request frame should look like this (as to my humble knowledge):
01 03 02 60 00 01 85 AC
For history of the issue please also see my previous post: “Modbus COMMUNICATION_ERROR ModbusIOException”
Any ideas on where the issue is (in front of or inside the computer?)
Your help is highly appreciated!