Schneider Electric 890USE17700 User Manual
Connection Example
148
890USE17700 April 2004
List of Supported
Function Codes
and Their
Descriptions
Function Codes
and Their
Descriptions
The following table lists the function codes that can be used by Modbus over TCP/
IP masters that communicate with the STB NIP 2212:
IP masters that communicate with the STB NIP 2212:
Modbus over
TCP/IP Data
Exchange
TCP/IP Data
Exchange
The following table describes the general process used by Modbus over TCP/IP
masters to exchange data with the STB NIP 2212.
masters to exchange data with the STB NIP 2212.
List of Exception
Codes
Codes
The following table describes the exception codes that Modbus over TCP/IP uses to
indicate an error condition:
indicate an error condition:
Modbus
Function
Code
Function
Code
Subfunction
or Subindex
or Subindex
Hexadecimal Description
3
0x03
read output holding registers (4x)
4
0x04
read input registers (3x)
6
0x06
write single register (4x)
8
sub index 21
0x08
get/clear Ethernet statistics (See Ethernet
Statistics, p. 136)
Statistics, p. 136)
16
0x10
write multiple (output) registers (4x)
22
0x16
mask write registers (4x)
23
0x17
read/write multiple registers (4x)
Stage
Action
1
Execute a function, specify the function code and the register address of the
selected input or output channel.
selected input or output channel.
2
The Modbus master (i.e., PC, PLC) sends a request to the STB NIP 2212.
z
If no exception is returned, the STB NIP 2212 responds to the master by
sending the data that was requested.
sending the data that was requested.
z
If a request contains an error, the STB NIP 2212 returns an exception code
to the master.
to the master.
Code in Hexadecimal
Description
0x01
illegal function
0x02
illegal data address
0x03
illegal data value
0x04
slave device failure