Hello,

Set the Mode value as 4 for RS485  Half duplex communication , by default its 0 of MB_Comm_load block. 

Use the modview simulator software as modbus slave for testing.

See the attached screen shot

Felipe_MCosta

Thank you so much. I tested it here and it worked.

I assign the value to the first scan.

 Good day.

Could you perhaps post a sample code i have been struggling and can not seem to get it going.

Regards

Hello I have the same setup and problem.

I try this solution but no connection. The Busy output of the master block stays True.

I use Modbus RTU V3.0 on the CPU 1512 V2.0 and has done the Firmware upate 6ES7512-1DK01-0AB0_V205. Connection on CP RS485 terminal 12 and 14.

I am sure that the slave is working and is available because I can make a working connection between the Slave and a S7-1212 PLC. Modbus adres 10.

Please Help. 

For Using ET200SP Module 6ES7 137-6AA00-0BA0 in RS485-2 wire mode. 

Declare in the Interface of the hardware properties for CM_ptp

Points to be taken care of are 

1. Terminals to be used for wiring are 12 and 14. 

2. In first network move 4 to "Modbus_Comm_Load_DB"s  "MODE" parameter. Ucan Use first scan or direct move option to move value. 

3. After moving the value then only call the "Modbus_Comm_Load" block. with the first scan at REQ 

4. Then call Modbus Master or Modbus Slave Block.