GE 1601-0149-A2 manual Modbus Functions Function Code 16 Store Multiple Setpoints

Modbus Functions

Function Code 16: Store Multiple Setpoints

489

Communications Guide

Modbus Implementation: Preset Multiple Registers

489 Implementation: Store Multiple Setpoints

This function code allows multiple Setpoints to be stored into the 489 memory. Modbus “registers” are 16-bit (two byte) values transmitted high order byte first. Thus all 489 setpoints are sent as two bytes. The maximum number of Setpoints that can be stored in one transmission is dependent on the slave device. Modbus allows up to a maximum of 60 holding registers to be stored. The 489 response to this function code is to echo the slave address, function code, starting address, the number of Setpoints stored, and the CRC.

Message Format and Example:

Request slave 11 to store the value 01F4 to Setpoint address 1180 and the value 0001 to setpoint address 1181. After the transmission in this example is complete,

489 slave 11 will have the following setpoints information stored:

Address	Data
1180	01F4
1181	0001
Master Transmission		Bytes	Example	Description
Slave Address		1	0B	message for slave 11
Function Code		1	10	store setpoints
Data Starting Address		2	11 80	data starting at 1180h
Number of Setpoints		2	00 02	2 setpoints = 4 bytes total
Byte Count		1	04	2 registers = 4 bytes
Data 1		2	01 F4	data for address 1180h
Data 2		2	00 01	data for address 1181h
CRC (low, high)		2	9B 89	computed CRC error code
Slave Response		Bytes	Example	Description
Slave Address		1	0B	message from slave 11
Function Code		1	10	store multiple setpoints
Data Starting Address		2	11 80	data starting at 1180h
Number of Setpoints		2	00 02	2 setpoints (4 bytes total)
CRC (low, high)		2	45 B6	computed CRC error code

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