Hi all,

I have similar problem with Modbus RTU, so i decide ask for advise without create duplicate topics.

Problem: I don't get "Done" from Master block. Once in first cycle it generate error "80CB". I check configuration on both sides (master and slave) and looks the same. If have someone advice where i should look or check, i I will be very thankful.

Cfg hw:

Master - CPU 1211C DC/DC/DC, 6ES7 211-1AE40-0XB0, V4.1 with

              CM 1241 (RS422/485), 6ES7 241-1CH32-0XB0, V2.1

Slave - Modbus Slave (from modbustools)

Connection by RS485 (pin 3 - B , 8 - A and ground - 1 according to the datasheet)

Attachment include photos of configuration and prj (if it's will be more useful for someone)

Thank you for attention.

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Split from CM 1241 modbus trouble shoot.