ProSoft Technology MVI56E-MCMR - Manual (Page 65)

MVI56E-MCMR ♦ ControlLogix Platform Configuring the MVI56E-MCMR Module
Modbus Communication Module with Reduced Data Block User Manual
ProSoft Technology, Inc. Page 65 of 225
May 13, 2014
If our device listed above shows its addressing as follows:
Then: To read "Switch_Input_Status", you would use Function Code 4 and
use a MB Address in Device of 512.
2.3.6 Master Command Examples
Read Holding Registers 4x (Modbus Function Code 3)
The 4x Holding Registers are used for storing analog values such as pressure,
temperature, current, program counters, timer accumulators and presets, and so
on. Holding Registers store values in 16-bit memory registers. These 16-bit
values can be interpreted in different ways that allow Holding Registers to hold
many different data types, such as 8-bit, 16-bit, 32-bit, or 64-bit signed or
unsigned integers, as well as 32-bit or 64-bit floating-point data (page 74) and
other data types.
The following illustration shows the correct parameter values to create a
command to read Modbus addresses 40001 to 40010 from Modbus Slave Device
Address 1.