Viewing and Exporting Modbus Addresses

The SLM-MX Configurator provides tools for viewing and exporting Modbus address mappings for your SLM-MX device and connected modules.

Viewing Modbus Addresses

To view the Modbus address mappings:

1. Connect to your SLM-MX device

2. Navigate to the “Modbus Registers Map” tab

3. Select a module from the list to view its Modbus address mapping

4. The address mapping will be displayed in a table format showing:

Note

If there are more than 8 channels, or contains status registers, the module will be split into multiple tables, it is necessary to scroll the module’s table to view the entire mapping.

Module I/O (Modbus Address Range)

• Module channel number

• Register type (Input Status, Coil, Holding Register, Input Register)

• Address offset (zero-based)

• Data length

Module Status Registers (Modbus Address Range)

• Status Register Description

• Register type (Input Status, Holding Register)

• Address offset (zero-based)

• Data length (if SLM Status Register)

All analog input modules, as well as some specialty modules have status registers. You can reach this by scrolling down the module’s table.

With the exception of SLM-MX Registers, which has two 16-bit registers at Holding Registers offset 200-201, all module status bits can be reached starting at Input Status offset 1000. All module status bits addressed sequentially based on the order they appear.

Understanding Modbus Mapping

The Modbus mapping follows standard Modbus conventions and are determined by the module type:

Start Address	Type	Access	Module Type
000001	Coils	Read/Write	Discrete Output
100001	Discrete Inputs	Read-Only	Discrete Output
300001	Input Registers	Read-Only	Analog Input
400001	Holding Registers	Read/Write	Analog Output/SLM-MX Status

When accessing modbus registers, most clients will ask for the type of register (coil, discrete input, etc.) and the address offset.

For example, if you want to read the value of the first 8 status bits starting at offset 1000, you would use the following

Python (pymodbus)

status_bits = client.read_discrete_inputs(1000, 8)

Productivity Suite

Note

Zero-based indexing is checked

Codesys

Note

Codesys offsets are 0-based, but asks for the offset in hexadecimal. In this case, offset 1000 is 0x3E8

Exporting Modbus Addresses

To export the Modbus address mappings:

1. Navigate to the “Modbus Mapping” tab

2. Click the “Export Map” button on the bottom right.

3. Define the file name and location, it will end with .csv

4. Click “Save”

Using Exported Mappings

The exported Modbus mappings will have the very specific order of descritpion.

Slot Order	Module Name	Channel	Register Type	Adress Offset	Modbus Address	Float Behavior	Status Register

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