GE Industrial Solutions EntelliGuard TU Trip Units - Manual (Page 62)

EntelliGuard TU Trip Units: UL/ANSI Models DEH-4567B
Serial Communication
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Table 8-4: Modbus Packet Format for Function Code 05H
Master
Transmission Bytes Example Description
Slave Address 1 11 message for slave
17
Function Code 1 05 execute operation
Operation Code 2 00 6C operation code
108
Code Value 2 FF 00 perform function
CRC 2 4E B7 CRC error code
Slave Response Bytes Example Description
Slave Address 1 11 message from
slave 17
Function Code 1 05 execute operation
Operation Code 2 00 6C operation code
108
Code Value 2 FF 00 perform function
CRC 2 4E B7 CRC error code
Function Code 06H
Modbus Implementation:
Preset Single Register
EntelliGuard Trip Unit Implementation:
Store Single Setpoint
This command allows the master to store a single setpoint
into the memory of an EntelliGuard Trip Unit. The slave
response to this function code is to echo the entire master
transmission.
For example, request slave 17 to store the value 2 in
setpoint address 215 (00 D7). After the transmission in this
example is complete, setpoints address 215 will contain the
value 2. The master/slave packet format is shown below:
Table 8-5: Modbus Packet Format for Function Code 06H
Master
Transmission Bytes Example Description
Slave Address 1 11 message for slave
17
Function Code 1 06 store single
setpoint
Data Starting
Address 2 00 D7 setpoint address
00 D7
Data 2 00 02 data for setpoint
address00 D7
CRC 2 BA A3 CRC error code
Slave Response Bytes Example Description
Slave Address 1 11 message from
slave 17
Function Code 1 06 store single
setpoint
Data Starting
Address 2 00 D7 setpoint address
04 5C
Data 2 00 02 data stored in
setpoint address
00 D7
CRC 2 BA A3 CRC error code
Function Code 10H
Modbus Implementation:
Preset Multiple Registers
EntelliGuard Trip Unit Implementation:
Store Multiple Setpoints
This function code allows multiple Setpoints to be stored
into the EntelliGuard Trip Unit memory. Modbus “registers”
are 16-bit (two byte) values transmitted high order byte
first. Thus all EntelliGuard Trip Unit 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 EntelliGuard Trip Unit 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 00 D7 and the value 01 F4
to setpoint address 04 5D. After the transmission in this
example is complete, EntelliGuard Trip Unit slave 17 will
have the following setpoints information stored: The
master/slave packets have the following format:
Table 8-6: Modbus Packet Format for Function Code 10H
Master
Transmission Bytes Example Description
Slave Address 1 11 message for slave
17
Function Code 1 10 store setpoints
Data Starting
Address 2 04 5C setpoint
address 04 5C
Number of
Setpoints 2 00 02 2 setpoints = 4
bytes total
Byte Count 1 04 4 bytes of data
DATA 1 2 00 02 data for setpoint
address 04 5C
DATA 2 2 01 F4 data for setpoint
address 04 5D
CRC 2 31 11 CRC error code