Hi,

Last time I used Modbus RTU was on a Basic IoT2050 FS04 with image v1.2.2 and it worked fine. I have a 2nd plant to monitor over Modbus RTU and I purchased a new Basic IoT2050 FS05 and installed example image v1.3.1. I setup the serial port as RS485 and used the same NodeRED flows as the previous. The node-red-contrib-modbus returns on every poll CRC error.

I double checked the wiring by:

1. moving the D-sub9 from IoT to my USB-serial converter and the Modbus Master (software running on my laptop) is getting answer from the Modbus slave.
2. plugging the D-sub9 back to the IoT and simulated a slave from my laptop. I still get the same CRC error.

I further troubleshooted by:

1. installing the example image v1.2.2 as I used before with the same result.
2. uninstall/reinstall different version of node-red-contrib-modbus without any better result.

In both cases, I think the RS485 as well as the modbus-flex-getter are correctly configured because the node gets status "connected" when the flow is deployed. I'm beginning to wonder if Siemens did any changes from FS04 to FS05? attached my test nodes

Regards,

Yoann