Function Code 10H - GE 350 Communications Manual

FUNCTION CODE 10H

Function Code 10H
9–6
Modbus Implementation: Preset Multiple Registers
350 Implementation: Store Multiple Setpoints
This function code allows multiple Setpoints to be stored into the 350 memory. Modbus
"registers" are 16-bit (two byte) values transmitted high order byte first. Thus all
350 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 350 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, 350 slave 17 will have the following setpoints information stored:
Address
04 5C
04 5D
The master/slave packets have the following format:
Table 9-8: MASTER/SLAVE PACKET FORMAT FOR FUNCTION CODE 10H
MASTER TRANSMISSION
SLAVE ADDRESS
FUNCTION CODE
DATA STARTING ADDRESS
NUMBER OF SETPOINTS
BYTE COUNT
DATA 1
DATA 2
CRC
SLAVE RESPONSE
SLAVE ADDRESS
FUNCTION CODE
DATA STARTING ADDRESS
NUMBER OF SETPOINTS
CRC
Data
00 02
01 F4
BYTES EXAMPLE
1 11
1 10
2 04 5C
2 00 02
1 04
2 00 02
2 01 F4
2 31 11
BYTES EXAMPLE
1 11
1 10
2 04 5C
2 00 02
2 82 7A
350 FEEDER PROTECTION SYSTEM – COMMUNICATIONS GUIDE
CHAPTER 9: MODBUS FUNCTIONS
DESCRIPTION
message for slave 17
store setpoints
setpoint address 04
5C
2 setpoints = 4 bytes
total
4 bytes of data
data for setpoint
address 04 5C
data for setpoint
address 04 5D
CRC error code
DESCRIPTION
message from slave
17
store setpoints
setpoint address 04
5C
2 setpoints
CRC error code