Ge 489 User Manual download pdf (Page 168)

6-6 489 Generator Management Relay GE Multilin

6.2 MODBUS FUNCTIONS 6 COMMUNICATIONS

6.2.7 FUNCTION CODE 16: STORE MULTIPLE SETPOINTS

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) val-

ues 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 regis-

ters 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 (hex):

SLAVE ADDRESS 1 0B message for slave 11

FUNCTION CODE 1 10 store setpoints

DATA STARTING ADDRESS 2 11 80 data starting at 1180

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 1180

DATA 2 2 00 01 data for address 1181

CRC 2 9B 89 CRC calculated by the master

SLAVE RESPONSE: BYTES EXAMPLE (hex):

SLAVE ADDRESS 1 0B response message from slave 11

FUNCTION CODE 1 10 store setpoints

DATA STARTING ADDRESS 2 11 80 data starting at 1180

NUMBER OF SETPOINTS 2 00 02 2 setpoints (4 bytes total)

CRC 2 45 B6 CRC calculated by the slave

1 2 ... 163 164 165 166 167 168 169 170 171 172 173 ... 258 259

No comments

Ge 489 User Manual Page 168