GE 469

6-4 469 Motor Management Relay GE Power Management
6.2 SUPPORTED MODBUS FUNCTIONS 6 COMMUNICATIONS
6
6.2 SUPPORTED MODBUS FUNCTIONS 6.2.1 OVERVIEW
The following functions are supported by the 469:
• 01 - Read Relay Coil
• 02 - Read Digital Input Status
• 03 - Read Setpoints and Actual Values
• 04 - Read Setpoints and Actual Values
• 05 - Execute Operation
• 06 - Store Single Setpoint
• 07 - Read Device Status
• 08 - Loopback Test
• 16 - Store Multiple Setpoints
6.2.2 FUNCTION CODES 01/02: READ RELAY COIL / DIGITAL INPUT STATUS
Modbus implementation: Read Coil and Input Status
469 Implementation: Read Relay Coil and Digital Input Status
For the 469 implementation of Modbus, these commands can be used to read Relay Coil Status or Digital Input
Status.
a) FUNCTION 01
The standard implementation requires the following: slave address (one byte), function code (one byte), start-
ing relay coil (two bytes), number of coils to read (two bytes), and CRC (two bytes). The slave response is the
slave address (one byte), function code (one byte), relay coil mask byte count (one byte; always 01 since only
six relay coils), bit mask indicating the status of requested relay coils (one byte), and CRC (two bytes).
b) FUNCTION 02
The standard implementation requires the following: slave address (one byte), function code (one byte), start-
ing digital input (two byte), number of digital inputs to read (two bytes), and CRC (two bytes). The slave
response is the slave address (one byte), function code (one byte), byte count of digital input mask (one byte),
bit mask indicating the status of requested digital inputs (one or two bytes), and CRC (two bytes).
Note: the CRC is sent as a two byte number with the low order byte sent first.