Sel 551 - Controlling Output Contacts

G.11
Date Code 20110408 Instruction Manual SEL-551 Relay
Modbus RTU Communications Protocol
Modbus RTU Communications Protocol
The relay responses to errors in the query are shown below:
Controlling Output
Contacts
The SEL-551 Modbus Register Map (Table G.18) includes three fields that
allow a Modbus master to force the relay to perform a variety of operations.
Use Modbus function codes 06h or 10h to write the appropriate command
codes and parameters into the registers shown in Table G.15. If function code
06h is used to write to a command code that has parameters, the parameters
must be written before the command code.
Table G.16 defines the command codes, their function and associated
parameters, and the Modbus function code used to initiate the related
command code.
Error Error Code Returned
Communication Counter
Increments
Incorrect/Illegal
query data length
Illegal Data Value (03h) Bad Packet Format
Invalid subfunction code Illegal Data Value (03h) Illegal Function Code/Op Code
Illegal register address Illegal Data Address (02h) Invalid Address
Table G.15 SEL-551 Modbus Command Region
Address Field
0090h Command Code
0091h Parameter 1
0092h Parameter 2
Table G.16 Modbus Command Codes
Command
Code
Function Parameter Definition
Modbus
Function
Code
01 Open No Parameter 06h, 10h
02 Close No Parameter 06h, 10h
03 Reset
Targets
No Parameter 06h, 10h
04 Trigger No Parameter 06h, 10h
05 Pulse OUT1 1–30 seconds duration (defaults to 1 second) 06h, 10h
06 Pulse OUT2 1–30 seconds duration (defaults to 1 second) 06h, 10h
07 Pulse OUT3 1–30 seconds duration (defaults to 1 second) 06h, 10h
08
a
a
SEL-551 only.
Pulse OUT4 1–30 seconds duration (defaults to 1 second) 06h, 10h
09
a
Pulse
Alarm
1–30 seconds duration (defaults to 1 second) 06h, 10h
10 Switch
Protocol
b
b
Switches the serial port protocol to SEL ASCII, the baud rate, parity, stop bits, and flow
control remain the same.
0080h 06h, 10h
11
c
c
Parameter of Command code 11 is bit masked to allow you to manipulate several data regions
simultaneously.
Reset
Data
Regions
0000 0000 0000 0001 Demand Metering
0000 0000 0000 0010 Peak Metering
0000 0000 0000 0100 History Buffer
0000 0000 0000 1000 Communication Counters
06h, 10h