GE Multilin 750/760 Feeder Management Relay 7-7
7 COMMUNICATIONS 7.3 MODBUS OPERATIONS
7
f) FUNCTION CODE 10H: STORE MULTIPLE SETPOINTS
This function code allows the master to modify the contents of a one or more consecutive setpoint registers in a 750/760.
Setpoint registers are 16 bit (two byte) values transmitted high order byte first. The maximum number of setpoint registers
that can be stored in a single packet is 60. The table below shows the format of the master and slave packets. It shows a
master device storing the value 200 at memory map address 1100h, and the value 1 at memory map address 1101h to
slave device 11.
7.3.2 EXCEPTION RESPONSES
Programming or operation errors happen because of illegal data in a packet, hardware or software problems in the slave
device, etc. These errors result in an exception response from the slave. The GE Multilin 750/760 implements the error
codes listed below. The slave detecting one of these errors sends a response packet to the master with the high order bit of
the function code set to 1. The following table shows the format of the master and slave packets. The example shows a
master device sending the unsupported function code 39h to slave device 11.
MASTER QUERY MESSAGE: EXAMPLE (HEX):
SLAVE ADDRESS 11 query message for slave 11
FUNCTION CODE 10 store multiple setpoint values
DATA STARTING ADDRESS: high order byte, low order byte 11 00 data starting at address 1100
NUMBER OF SETPOINTS: high order byte, low order byte 00 02 2 setpoint values = 4 bytes total
BYTE COUNT 04 4 bytes of data
DATA #1: high order byte, low order byte 00 C8 data for address 1100 = 00C8
DATA #2: high order byte, low order byte 00 01 data for address 1101 = 0001
CRC: low order byte, high order byte 27 01 CRC computed by master
SLAVE RESPONSE: EXAMPLE (HEX):
SLAVE ADDRESS 11 response message from slave 11
FUNCTION CODE 10 store multiple setpoint values
DATA STARTING ADDRESS: high order byte, low order byte 11 00 data starting at address 1100
NUMBER OF SETPOINTS: high order byte, low order byte 00 02 2 setpoint values = 4 bytes total
CRC: low order byte, high order byte 46 64 CRC computed by slave
MASTER QUERY MESSAGE: EXAMPLE (HEX):
SLAVE ADDRESS 11 query message for slave 11
FUNCTION CODE 39 unsupported function code – error
CRC: low order byte, high order byte CD F2 CRC computed by master
SLAVE RESPONSE: EXAMPLE (HEX):
SLAVE ADDRESS 11 response message from slave 11
FUNCTION CODE B9 return unsupported function code with high-order bit set
ERROR CODE 01 illegal function
CRC: low order byte, high order byte 93 CRC computed by slave
Courtesy of NationalSwitchgear.com
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