Understanding the Internal Registers

Overview

This topic describes configuring a Momentum 170ENT11001 using the Modbus TCP/IP protocol.

Background

The adapter contains three groups of internal registers that enable the adapter to:

transfer input or output data at the I/O base adapter’s field terminals:
- data group registers
set or retrieve the adapter’s configuration:
- configuration group registers
monitor system status:
- status group registers

All three register groups can be accessed as 4x (400) references by MSTR function blocks over the Ethernet network by standard Modbus commands to ensure compatibility with existing devices.

The user can access various registers to obtain I/O module information via the Ethernet network. These internal registers are mapped to emulate 4x (400) registers allowing read/write 4x (400) register commands to be used for example by using an MSTR block.

Those same registers can be accessed through the Web pages as discussed in Accessing the Momentum 170ENT11001 through Embedded Web Pages. Accessing through the Web pages provides a friendlier GUI for configuring the registers.

Following is a diagram that shows the data flow between the Ethernet network and the Ethernet communication adapter’s internal registers.

Data flow diagram