Hello

I have problem with Modbus communication between s7 300 and display. DLL11 (Display) works in modbus RTU standard (RS 485) - slave. 

I want to display anything or enter value into register 7500.

I used:

1. ET 200 6ES7 151-1BA02-0AB0

2. 1 SI Modbus Master (4B) 6ES7 138-4DF11-0AB0
 

and blocks FB2 (S_SEND) and FB3 (S_RCV).

But when i send anything appears the error 1E03 (Error during communication between the serial interface and CPU).

I add my program with hardware and display documentations https://www.lumel.com.pl/resources/Pliki%20do%20pobrania/wyswietlacze/DL11/DL11_DL12_DL13_service_manual.pdf. 

I'm just learning controller programming so I'm counting on your support. :)