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8 COMMUNICATIONS
Modbus Implementation:
GE Power Management Implementation:
This function code allows the master to modify the contents of a one or more consecutive setpoint registers in
the addressed slave device. Setpoint registers are 16 bit (two byte) values transmitted high order byte first.
The maximum number of register values (setpoints) that can be stored in a single message is 60.
MESSAGE FORMAT AND EXAMPLE:
Request slave device 11 to write the value 00C8 at setpoint address 1100, and the value 0001 at setpoint
address 1101.
Master Query Message:
SLAVE ADDRESS
FUNCTION CODE
DATA STARTING ADDRESS: high order byte
DATA STARTING ADDRESS: low order byte
NUMBER OF SETPOINTS: high order byte
NUMBER OF SETPOINTS: low order byte
BYTE COUNT
DATA #1: high order byte
DATA #1: low order byte
DATA #2: high order byte
DATA #2: low order byte
CRC: low order byte
CRC: high order byte
Field:
SLAVE ADDRESS
FUNCTION CODE
DATA STARTING ADDRESS: high order byte
DATA STARTING ADDRESS: low order byte
NUMBER OF SETPOINTS: high order byte
NUMBER OF SETPOINTS: low order byte
CRC: low order byte
CRC: high order byte
GE Power Management
8.2.12 FUNCTION CODE 10H: STORE MULTIPLE SETPOINTS
Preset Multiple Registers
Store Multiple Setpoints
Example (hex):
11
query message for slave 11
10
store multiple setpoint values
11
data starting at address 1100
00
00
2 setpoint values = 4 bytes total
02
04
4 bytes of data
00
data for address 1100 = 00C8
C8
00
data for address 1101 = 0001
01
27
01
Example (hex):
11
response message from slave 11
10
store multiple setpoint values
11
data starting at address 1100
00
00
2 setpoint values = 4 bytes total
02
46
64
745 Transformer Management Relay
8.2 MODBUS PROTOCOL
8-9
8
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