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MODBUS Slave Gateway

Owned by Kaitlin Luong
Last updated: Jun 07, 2024
2 min read

The CTM is a remote wireless gateway physically connected to another MODBUS Slave Device. The Slave Gateway can communicate with local devices via Ethernet, RS232, RS485, or GPIO Input/Output (Self Slave). Typically, the Slave Gateway communicates via a single protocol, such as RS232, although simultaneous communication via RS232 and Ethernet is also possible.

Setting Name

Descriptions

Value

Mode

Configure device to act as a Slave Gateway

MODBUS Gateway Slave

WAN Encapsulation

Protocol used to communicate with remote Master Gateway

TCP or RTU over UDP - Should match Master Gateway

Navigate to network → access → MODBUS RS-232 Access or MODBUS RS-485 Access

Enable WWAN access to serial data for Master

Enable and port number

Remote MODBUS Gateway Slaves

  1. Name

  2. ID

  3. Target

  4. TCP Slave IP

Slave Gateway requires a list of all the slaves connected to it and their pre-determined addresses.

  1. Friendly Name

  2. Slave ID

  3. Self-Slave, TCP Slave, Serial ASCII, Serial RTU

  4. LAN IP of TCP Slaves only. Else leave as 0.0.0.0.

Example of configuring a MODBUS TCP Slave with the CTM serving as the Master Slave Gateway:

  1. Choose a Serial mode, either RS232 or RS485, and configure it as "MODBUS".

Baud Rate settings are unnecessary unless there is a slave device utilizing RS-232 or RS-485.

image-20240422-162327.png

  1. Configure the Serial port selected, either RS232 or RS485 to the “MODBUS Gateway Slave” mode.

image-20240422-162456.png

  1. Expand the “MODBUS Gateway Settings”. Make sure the WAN Encapsulation is set to TCP for MODBUS TCP (MODBUS RTU over UDP is also supported).

  1. Expand the “MODBUS Gateway Settings” → “MODBUS Gateway Slave Settings

    and define the “Local Slave Devices”.

Select Save and Apply and the MODBUS TCP slave device will communicate with the MODBUS Master.

Example of a MODBUS Gateway Slave using connected to an RS232 MODBUS Device

Example of Two MODBUS Slave devices connected to MODBUS Slave Gateway, one TCP one RS232

 

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