Modbus Configuration in SEL Relays
Key Takeaway
How to configure Modbus RTU and TCP in SEL relays for reading metering, protection status, and relay word bits from SCADA and energy management systems.
Quick Answer
SEL relays expose metering (currents, voltages, power, energy, frequency) and status data via Modbus holding registers. Configure slave address in Quickset (E MADDR), select serial port or Ethernet, and read using FC03. Register addresses are in each relay's instruction manual.
When to Use Modbus vs DNP3
Modbus for simple metering integration and energy management. DNP3 for full SCADA with event reporting and timestamps. Modbus has no event reporting — polling only.
Register Map
SEL publishes Modbus register maps in instruction manuals. Metering values are 16-bit integers with scale factors. Protection status uses bit-packed registers. See Modbus register types for the data model.
Integration
Configure Ignition or Geo SCADA to read SEL metering for energy dashboards and billing systems.
Frequently Asked Questions
Yes. Phase currents, voltages, power, energy, frequency, and power factor are exposed as holding registers readable via FC03.
E MADDR in Quickset. Valid 1-247. Each relay on an RS-485 bus must have a unique address.