Application functions - Arc protection - Auto synchronization - Bay control and measurement - Merging unit - Transformer protection - 2 winding - Feeder protection - Voltage regulation - Capacitor bank protection - Petersen Coil control - Grid automation - Busbar differential protection (high impedance) - Back-up protection - Motor protection - Busbar protection (voltage and frequency) - Transformer protection - 3 winding - Interconnection protection - Generator protection - Power management/Load shedding - Modbus Communication Manual - REX640 Protection and control - PCL4 - IEC - ANSI - 16.02.2023

REX640 Modbus Communication Protocol Manual

Table 1. Supported application functions
Function code	Name	Description
01	Read coil status	Reads the status of discrete outputs.
02	Read digital input status	Reads the status of discrete inputs.
03	Read holding registers	Reads the contents of output registers.
04	Read input registers	Reads the contents of input registers.
05	Force single coil	Sets the status of a discrete output.
06	Preset single register	Sets the value of a holding register.
08	Diagnostics	Checks the communication system between the client and the server.
15	Force multiple coils	Sets the status of multiple discrete outputs.
16	Preset multiple registers	Sets the value of multiple holding registers.
23	Read/write holding registers	Exchanges holding registers in one query.