Siemens S7-1200 PLC Program for Modbus RTU Data Acquisition

I developed a program in SCL (Structured Control Language) – learning it on the go – to read data from 15 Modbus RTU slave devices (power analyzers) using a Siemens S7-1200 PLC. The data was stored in a Data Block (DB) and then sent to a SCADA system for monitoring.

Communication Setup:

• 15 power analyzers connected in series via RS-485

• RS-485 signals converted to Ethernet using an RS-485-to-Ethernet converter

• Data received by the S7-1200 PLC