Title:
Modbus Master Communication on PowerLogic P5 Protection Relays
Issue:
How to configure and use Modbus Master protocol for PowerLogic P5 relays to communicate with external devices.
Product:
PowerLogic P5 Protection Relay
Environment:
Industrial automation systems
Serial RS-485 networks (two-wire or four-wire)
Integration with third-party devices (meters, sensors, controllers)
Configuration tools: eSetup Easergy Pro, Web HMI
Cause:
Modbus Master mode allows the relay to actively poll and control external devices. Incorrect configuration of addresses, register mapping, or communication parameters can result in data errors or loss of control.
Resolution:
- Protocol Support:
- Available only on serial ports (RS-485 or fiber)
- Configurable via COMMUNICATION menu or eSetup Easergy Pro
- Functionality:
- Reads analog and digital inputs from external devices
- Writes digital outputs for control
- Supports up to 64 analog inputs, 18 digital inputs, and 16 digital outputs
- Configuration Steps:
- Select Modbus Master as the serial protocol
- Define slave addresses and register mapping for each external device
- Configure baud rate (1200–115200 bps), parity, and timeout settings
- Assign names and scaling factors for imported data points
- Features:
- Custom naming for external points
- Integration with relay logic and protection functions
- Supports cyclic polling and exception handling
- Security:
- No encryption; use physical port hardening and network segmentation
- Disable unused ports and protocols to reduce exposure
- Integration:
- Ideal for connecting sensors, meters, or other Modbus-compatible equipment
- Data can be used in relay logic, alarms, and SCADA reporting
