Section 3
1MAC052634-MB D
Vendor-specific implementation
14
615/620 series ANSI
Communication Protocol Manual
Table 5:
Common (instance independent) Modbus TCP/IP diagnostic counters
3.2
Supported function codes
3.2.1
Application functions
Table 6:
Supported application functions
3.2.2
Diagnostic functions
The diagnostic functions are only intended for serial communication. However, the serial
diagnostic counters can be read, but not reset, via the Modbus TCP/IP interface. The serial
line cannot be forced to the listen mode via the Modbus TCP/IP interface.
Table 7:
Supported diagnostic subfunctions
Counter
Description
CnReject No
sockets
The amount of connection requests that are rejected due to unavailable TCP sockets.
CnReject Not reg
The amount of connection requests that are rejected since the client is not registered.
Function
code
Name
Description
01
Read coil status
Reads the status of discrete outputs.
02
Read digital input status
Reads the status of discrete inputs.
03
Read holding registers
Reads the contents of output registers.
04
Read input registers
Reads the contents of input registers.
05
Force single coil
Sets the status of a discrete output.
06
Preset single register
Sets the value of a holding register.
08
Diagnostics
Checks the communication system between
the master and the slave.
15
Force multiple coils
Sets the status of multiple discrete outputs.
16
Preset multiple registers
Sets the value of multiple holding registers.
23
Read/write holding registers
Exchanges holding registers in one query.
Function
code
Name
Description
00
Return query data
The data in the query data field is returned
(looped back) in the response. The entire
response is identical to the query.
01
Restart communication option
The slaves 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. If the port is in
the listen only mode, no response will be
sent.
04
Force listen only mode
The slave is forced to enter the listen only
mode for Modbus communication.
10
Clear counters and diagnostic register
All counters and the diagnostic register are
cleared.