CTI 2572-B - Supported Modbus Function Codes (FC); Modbus Exception Codes; Diagnostic Statistics

CTI 2572-B / 2500C-2572-B Installation and Operation Manual 20
5.4. Supported Modbus Function Codes (FC)
The following Function Codes are supported by the Modbus/TCP Server function.
FC (dec)
FC (hex)
Function Codes
505
Variable
Comments
01
01
Read Coil Status
C
Max number of coils = 2000
02
02
Read Input Status
X
Max number of inputs = 2000
03
03
Read Holding Register
V
Max = 125
04
04
Read Input Register
WX
Max = 125
05
05
Write Single Coil
C
06
06
Write Single Register
V
07
07
Read Exception Status
C
15
0F
Write Multiple Coils
C
Max = 800
16
10
Write Multiple Registers
V
Max = 100
5.5. Modbus Exception Codes
The following Modbus Exception codes may be returned to the Modbus Client in case of an error.
Code
Name
Description
01
Illegal Function
Unsupported Function code
02
Illegal Data Address
Requested data address not included in the PLC configuration
03
Illegal Data Value
Typically indicates a problem in the query structure
04
Slave Device Failure
Unrecoverable error occurred while processing the request
5.6. Diagnostic Statistics
A full set of diagnostic statistics is maintained for the Modbus/TCP server. These may be accessed by a web
browser by setting the URL to the IP address of the module. From the main menu page, select Module
Diagnostics and the Modbus/TCP Server.