Sel 751A - Table E.12 Responses to 04 H Read Input Register Query Errors; Table E.13 05 H Force Single Coil Command; Table E.14 01 H, 05 H SEL-751 A Output

E.10
SEL-751A Relay Instruction Manual Date Code 20100129
Modbus RTU Communications
Communications Protocol
The relay responses to errors in the query are shown in Table E .12 .
05h Force Single Coil
Command
Use function code 05h to set or clear a coil. In Table E.13, the command
response is identical to the command request.
Table E.14 lists the coil numbers supported by the SEL-751A. The physical
coils (coils 1–27) are self-resetting. Pulsing a Set remote bit (decimal address
59 through 99) causes the remote bit to be cleared at the end of the pulse.
A successful response from the slave will have the following format:
1 byte Slave Address
1 byte Function Code (04h)
1 byte Bytes of data (n)
n bytes Data (2–250)
2 bytes CRC-16
Table E.12 Responses to 04h Read Input Register Query Errors
Error Error Code Returned
Communication
Counter Increments
Illegal register to read Illegal Data Address (02h) Invalid Address
Illegal number of registers to read Illegal Data Value (03h) Illegal Register
Format error Illegal Data Value (03h) Bad Packet Format
Table E.11 04h Read Input Register Command (Sheet 2 of 2)
Bytes Field
Table E.13 05h Force Single Coil Command
Bytes Field
Requests from the master must have the following format:
1 byte Slave Address
1 byte Function Code (05h)
2 bytes Coil Reference
1 byte Operation Code (FF for bit set, 00 for bit clear)
1 byte Placeholder (00)
2 bytes CRC-16
Table E.14 01h, 05h SEL-751A Output (Sheet 1 of 4)
Coil Address (Decimal) Function Code Supported Coil Description
0 01, 05 Pulse OUT101 1 second
1 01, 05 Pulse OUT102 1 second
2 01, 05 Pulse OUT103 1 second
3 01, 05 Pulse OUT301 1 second
4 01, 05 Pulse OUT302 1 second
5 01, 05 Pulse OUT303 1 second