Hello,
I’ve tried to setup a modbus RTU client (rs485) on the TBR255 for a while now, but I can’t get it to work.
For this, “Modbus Serial Client” has been used.
The bus have three nodes connected; TBR255, a sensor over modbus, and a USB interface for send/receive. The TBR255 is using half-duple so I have bridged R+ & D+ as well as R- & D-.
I’ve tested this on two separate TBR255 devices, one that had firmware version TRB2_R_00.07.06.03, and one that was upgraded to the latest firmware: TRB2_R_00.07.06.10.
Whenever I try to test the client through the web admin, I get the error: "Failed to test request, check your configuration.
This is the configuration I have currently:
Modbus Device:
With registers
This is what I have tried so far
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Modbus Serial Server
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Modbus Serial Client
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MQTT Modbus Gateway
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Modbus TCP over Serial Gateway
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Hooked up a scope to the bus. The TBR255 never puts anything to the bus, nor does it reply to anything when it’s set up as a server.
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The ubus call modbus_client serial.test can’t be used with {“serial_type”: “/dev/rs485”}. Trying to use /dev/ttyUSB0 does not put anything on the bus.
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Running ls in the /dev folder returns no rs485 device. rs232 does show up.
Where do I go from here?