MVI56E-MCMR ♦ ControlLogix Platform
Configuring the MVI56E-MCMR Module
Modbus Communication Module with Reduced Data Block
User Manual
ProSoft Technology, Inc.
Page 59 of 223
Parameter
Description
ModBus Function
1
,
2
,
3
,
4
,
5
,
6
,
15
, and
16
(when viewed in the .CFG text file)
The Modbus Function Code determines what kind of command to
send to the slave device. Valid code numbers and descriptions for
this field are as follows:
Note:
The Modbus protocol specifies that the valid address range for
each Modbus data type can be x00001 to x65535. Most newer
Modbus devices support this addressing range. However, some older
Modbus devices may only support addresses that range from x0001
to x9999.
FC 1 = Read Coil (0X)
Use this Function Code to read Modbus Coil addresses 000001 to
065535 (or 0x0001 to 0x9999). These are read/write single-bit binary
values. Use Function Code 5 or 15 to write to these Coil addresses.
FC 2 = Read Input (1X)
Use this Function Code to read Modbus Input Status addresses
100001 to 165535 (or 1x0001 to 1x9999). These are read-only single-
bit binary values.
FC 3 = Read Holding Registers (4X)
Use this Function Code to read Modbus Holding Register addresses
400001 to 465535 (or 4x0001 to 4x9999). These are read/write 16-bit
word values. Use Function Code 6 or 16 to write to these Holding
Registers.
FC 4 = Read Input Registers (3X)
Use this Function Code to read Modbus Input Register addresses
300001 to 365535 (or 3x0001 to 3x9999). These are read-only 16-bit
word values.
FC 5 = Force Single Coil (0X)
Use this Function Code to write to Modbus Coil addresses. This
command will write to only one coil per command. Use Function
Code 15 to write to multiple coils in the same command.
FC 6 = Preset Single Register (4X)
Use this Function Code to write to Modbus Holding Registers. This
command will write to only one register per command. Use Function
Code 16 to write to multiple registers in the same command.
FC 15 = Force Multiple Coils (0X)
Use this Function Code to write multiple Coil values with one
command.
FC 16 = Preset Multiple Registers (4X)
Use this Function Code to write multiple Holding Register values with
one command.
