Profile Of Modbus - ABB REU 610 Technical Reference Manual

1MRS755769
5.1.15.1.
Voltage Relay
Technical Reference Manual

Profile of Modbus

The Modbus protocol ( ASCII or RTU) is selected via the HMI and can be used only
through the rear connection of the relay on the optional communication module.
Modbus line settings, that is, parity, CRC byte order and baud rate, can be adjusted
either via the HMI or the SPA bus.
The implementation of the Modbus protocol in REU 610 supports the following
functions:
Table 5.1.15.1.-1 Supported application functions
Function code
01
02
03
04
05
06
08
15
16
23
Table 5.1.15.1.-2 Supported diagnostic subfunctions
Code Name
00 Return query data
01 Restart
communication
option
04 Force listen only
mode
10 Clear counters and
diagnostic register
11 Return bus
message count
Function description
Read coil status
Reads the status of discrete outputs.
Read digital input status
Reads the status of discrete inputs.
Read holding registers
Reads the contents of output registers.
Read input registers
Reads the contents of input registers.
Force single coil
Sets the status of a discrete output.
Preset single register
Sets the value of a holding register.
Diagnostics
Checks the communication system between the
master and the slave.
Force multiple coils
Sets the status of multiple discrete outputs.
Preset multiple registers
Sets the value of multiple holding registers.
Read/write holding registers
Exchanges holding registers in one query.
Description
The data in the query data field is returned (looped back)
in the response. The entire response is to be identical to
the query.
The slave's peripheral port is initialized and restarted
and the communication event counters are cleared.
Before this, a normal response will be sent provided that
the port is not in the listen only mode. However, if the
port is in the listen only mode, no response will be sent.
The slave is forced to enter the listen only mode for
Modbus communication.
All counters and the diagnostic register are cleared.
The number of messages in the communications system
detected by the slave since its last restart, clear counters
operation or power up is returned in the response.
REU 610
61