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COMMUNICATIONS GUIDE RS485 INTERFACE (MODBUS RTU)
MM200 MOTOR MANAGEMENT SYSTEM – COMMUNICATIONS GUIDE 9
Function Code 10H Modbus Implementation: Preset Multiple Registers
MM200 Implementation: Store Multiple Setpoints
This function code allows multiple Setpoints to be stored into the MM200 memory. Modbus
“registers” are 16-bit (two byte) values transmitted high order byte first. Thus all MM200
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 MM200 response to this function code is to echo the
slave address, function code, starting address, the number of Setpoints stored, and the
CRC.
For example, consider a request for slave 17 to store the value 00 02 to setpoint address
04 5C and the value 01 F4 to setpoint address 04 5D. After the transmission in this example
is complete, MM200 slave 17 will have the following setpoints information stored:
The master/slave packets have the following format:
Table 8: MASTER/SLAVE PACKET FORMAT FOR FUNCTION CODE 10H
SLAVE RESPONSE BYTES EXAMPLE DESCRIPTION
SLAVE ADDRESS 1 11 message from
slave 17
FUNCTION CODE 1 08 loopback test
DIAG CODE 2 00 00 must be 00 00
DATA 2 00 00 must be 00 00
CRC 2 E0 0B CRC error code
Address Data
04 5C 00 02
04 5D 01 F4
MASTER TRANSMISSION BYTES EXAMPLE DESCRIPTION
SLAVE ADDRESS 1 11 message for slave
17
FUNCTION CODE 1 10 store setpoints
DATA STARTING ADDRESS 2 04 5C setpoint address
04 5C
NUMBER OF SETPOINTS 2 00 02 2 setpoints = 4
bytes total
BYTE COUNT 1 04 4 bytes of data
DATA 1 2 00 02 data for setpoint
address 04 5C
DATA 2 2 01 F4 data for setpoint
address 04 5D
CRC 2 31 11 CRC error code
SLAVE RESPONSE BYTES EXAMPLE DESCRIPTION
SLAVE ADDRESS 1 11 message from
slave 17
FUNCTION CODE 1 10 store setpoints
DATA STARTING ADDRESS 2 04 5C setpoint address
04 5C
NUMBER OF SETPOINTS 2 00 02 2 setpoints
CRC 2 82 7A CRC error code