Schweitzer Engineering Laboratories SEL-700G Series, Instruction Manual

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E.13
Date Code 20170814 Instruction Manual SEL-700G Relay
Modbus RTU Communications
Communications Protocol
Coil addresses start at 0000 (for example, Coil 1 is located at Coil address
0000). If the device is disabled it responds with error code 4 (Device Error). In
addition to Error Code 4, the device responses to errors in the query are shown
in Table E.15.
06h Preset Single
Register Command
The SEL-700G uses this function to allow a Modbus master to write directly
to a database register. Refer to the Modbus Register Map in Table E.34 for a
list of registers that can be written by using this function code. If you are
accustomed to 4X references with this function code, for six-digit addressing,
add 400001 to the standard database addresses.
In Table E.16, the command response is identical to the command the master
requires.
The relay responses to errors in the query are shown in Table E.17.
86 01, 05 Pulse RB28
a
87 01, 05 Pulse RB29
a
88 01, 05 Pulse RB30
a
89 01, 05 Pulse RB31
a
90 01, 05 Pulse RB32
a
a
Pulsing a Set remote bit causes the remote bit to be cleared at the end of the pulse (1 SEL
OGIC
Processing Interval).
Table E.15 Responses to 05h Force Single Coil Query Errors
Error Error Code Returned
Communications
Counter Increments
Invalid bit (coil) Illegal Data Address (02h) Invalid Address
Invalid bit state requested Illegal Data Value (03h) Illegal Register
Format Error Illegal Data Value (03h) Bad Packet Format
Table E.14 01h, 05h SEL-700G Output (Sheet 4 of 4)
Coil Address (Decimal) Function Code Supported Coil Description
Table E.16 06h Preset Single Register Command
Bytes Field
Queries from the master must have the following format:
1 byte Slave Address
1 byte Function Code (06h)
2 bytes Register Address
2 bytes Data
2 bytes CRC-16
Table E.17 Responses to 06h Preset Single Register Query Errors
Error Error Code Returned
Communications
Counter Increments
Illegal register address Illegal Data Address (02h) Invalid Address Illegal Write
Illegal register value Illegal Data Value (03h) Illegal Write
Format error Illegal Data Value (03h) Bad Packet Format