Modbus TCP

6 min

Review the following information for setting up and configuring the Modbus TCP driver.

Belden Horizon Data Operations Compatible Series

Compatibility parameter	Compatible items
Driver type	Ethernet
When to use	TCP connection to a Modbus device
Replaces Gen 1 driver(s)	Modbus TCP (Gen1) Modbus TCP-Offset (Gen1) Learn more about Gen1 and Gen2 Driver Differences

To set up and configure this device in Belden Horizon Data Operations, you will need to do the following:

Step 1: Set up and Configure the PLC Device
Step 2: Set up the PLC Device in Belden Horizon Data Operations DeviceHub
Step 3: Configure the List of Registers

Step 1: Set up and Configure the PLC Device

If the device is configured for Ethernet access, find its network parameters. Otherwise, use Automation Studio v4.6.2 software on your computer to configure the device for Ethernet access.

Step 2: Set up the PLC Device in Belden Horizon Data Operations DeviceHub

Configure the following parameters when you Connect a Device with this driver. Update default values to the specific setup of your device.

Parameter	Value
Type	Modbus
Driver	Modbus TCP
Network Address	The device address you defined in Step 1
Network Port	502
Station ID	0

Step 3: Configure the List of Registers

When you Add Tags to the connected device, refer to the following register table and tag parameters.

Refer to the following additional resources:

Register Table

Note: The address format in this Gen 2 driver is different from the Gen 1 driver (Modbus TCP (Gen1)) for the same device. Learn more about Gen1 and Gen2 Driver Differences.

Name	Data Type	Address Format in Belden Horizon Data Operations	Max Address	Description
D	bit	DDDD	9999	Discrete Input Contacts
C	bit	DDDD	9999	Discrete Output Coils
H	word	DDDD	9999	Analog Output Holding Registers
I	word	DDDD	9999	Analog Input Registers

Tag Parameters

Name: Select a register name from the drop-down list. The available options depend on the names in the register table.
Value Type: Select a data type from the drop-down list. The available options depend on the register name selected.
Polling Interval: Enter a value in seconds. This determines how often the tag should poll the register for data.
Tag Name: Enter a name for the tag.
Description (Optional): Enter a description for the tag.
Address: Enter a tag address. The value must in the decimal format, within the allowed min/max range. Omit the leading zeros. The device might use the decimal (D), hexadecimal (H), or octal (O) address format. For Bit tags, append the bit address without the bit separator. The lowercase letters in the address format indicate how many digits you should enter in the Bit address.
Count: Enter the number of register values to read. A count higher than 1 will generate an array of values from the address value configured and respective subsequent address values.
Endianness (not available for all names): This option configures how the tag data will be formatted and whether bytes and/or words will be counted from the start (big-endian style) or end (little-endian style) of strings of data. Select one of the following options.
- No Swap: Data will be formatted in big-endian style (bytes and words counted from the start). For example: AB CD.
- Swap Bytes: Only bytes will be formatted in little-endian style (counted from the end). For example: BA DC.
- Swap Words: Only words will be formatted in little-endian style (counted from the end). For example: CD AB.
- Swap Words & Bytes: Both words and bytes will be formatted in little-endian style (counted from the end). For example: DC BA.
Tag Formula: Enter a formula for the tag to process the generated data. Two variables are permitted: value (current tag value) and timestamp (current tag UNIX time in milliseconds). The following math functions are available:
- sin
- cos
- sqrt
- tan
- power
- log
- exp
Only Publish on Change of Value: Select the checkbox to customize NATS messages to be published only when the value parameter changes from a previous value to a new one. Change of Value only applies to boolean, numeric (such as int or float), and simple string data types. It does not apply to complex types, such as JSON or array. Poll-once topics will not be affected by Change of Value settings. These topics will still only see a single message.
Meta Data: Metadata summarizes basic information about data. This feature allows you to define key-value pair data for the device output payload later on. It can then be used to find, use, and reuse particular instances of data.