GE 239

GE Multilin 239 Motor Protection Relay 7-9
7 COMMUNICATIONS 7 COMMUNICATIONS
7
7.13 16: STORE MULTIPLE SETPOINTS
• Modbus Implementation:Preset Multiple Registers
• 239 Implementation: Store Multiple Setpoints
This function code allows multiple Setpoints to be stored into the 239 memory. Modbus "registers"
are 16 bit (two byte) values transmitted low order byte first. Thus all 239 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 239
response to this function code is to echo the slave address, function code, starting address, the num-
ber of Setpoints stored, and the CRC.
a) MESSAGE FORMAT AND EXAMPLE
Request slave 11 to store the value 0096 to Setpoint addresses 1028 and 1029. After the transmis-
sion in this example is complete, 239 slave 11 will have the following Setpoints information stored:
Address Data
1028 0096
1029 0096
Master Transmission Bytes Example (hex)
SLAVE ADDRESS - 1 byte 11 message for slave 11
FUNCTION CODE - 1 byte 10 store Setpoints
DATA STARTING ADDRESS - 2 bytes 10 Setpoint address 1028
28
NUMBER OF SETPOINTS - 2 bytes 00 2 Setpoints (4 bytes total)
02
BYTE COUNT - 1 byte 04 4 bytes of data
DATA 1 - 2 bytes 00 data for address 1028
96
DATA 2 - 2 bytes 00 data for address 1029
96
CRC - 2 bytes 09 CRC calculated by the master
53
Slave Response
SLAVE ADDRESS - 1 byte 11 message from slave 11
FUNCTION CODE - 1 byte 10 store Setpoints
DATA STARTING ADDRESS - 2 bytes 10 Setpoint address 1028
28
NUMBER OF SETPOINTS - 2 bytes 00 2 Setpoints
02
CRC - 2 bytes C7 CRC calculated by slave
90