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Multiple Modbus RTU Baud rates on LM4 - Printable Version

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Multiple Modbus RTU Baud rates on LM4 - Arlequin - 10.12.2016

Hello,

I have multiple Modbus slaves with various supported baud rates that I want to connect but due to the look of the RTU settings panel in the web interface, it seems that on LM4, only one of the 3 RS-485 ports can be used for Modbus RTU.

I have a pellet heater gateway that only supports 9600 baud, Schneider meters than supports from 9600 to 38400 baud and Embedded Systems Universal IO-20 that supports only 115200 baud.

How can I interface all these devices to the LM4 ? Is it possible to use an additional RS-485 port for Modbus RTU ?

RE: Multiple Modbus RTU Baud rates on LM4 - admin - 11.12.2016

UIO20 does support 9600 and other baudrates, but once you change RTU settings through ModBus tab you have to do the write address procedure again. This will write both the new address and serial settings.

RE: Multiple Modbus RTU Baud rates on LM4 - Arlequin - 11.12.2016

(11.12.2016, 08:39)admin Wrote: UIO20 does support 9600 and other baudrates, but once you change RTU settings through ModBus tab you have to do the write address procedure again. This will write both the new address and serial settings.

That's great news thanks, but I did not manage to change the settings, I don't have a programming button on my UIO20E device. I only see two unsoldered holes on the PCB on the bottom left, maybe I have to short these to go in programming mode ?

Can I also change parity to None using this procedure ?

RE: Multiple Modbus RTU Baud rates on LM4 - admin - 12.12.2016

Older UIO20 revisions had the button on the side, check for a hole there. Newer ones have the button next to LED1 and LED2. As for the serial settings, parity and stop bits are passed together with the baud rate.