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RS485 to Modbus TCP adapters

Use an RS485 to Modbus TCP adapter when a device only offers a serial interface, so the controller can reach it over the network.

Some devices only communicate over Modbus RTU (RS485). An RS485-to-Modbus TCP adapter converts that signal to Modbus TCP, so the controller can reach the device over the network.

Diagram of an RS485 device on the network. The device is connected with a twisted pair on terminals A and B to an RS485 adapter, and Modbus RTU runs over that line. The adapter is connected with a UTP cable to the EMS controller, and Modbus TCP runs there.

Once the adapter is configured, add the device like any other Modbus TCP device: see Adding and verifying devices.

In the wizard, enter:

  • IP address: the IP address of the adapter.
  • Port: the Modbus TCP port of the adapter, usually 502.
  • Slave ID: the Modbus address of the device on the RS485 line.
  • RTU over TCP (serial converter): switch this on when the adapter is a transparent converter that passes the serial frames on unchanged, rather than a Modbus gateway that converts Modbus RTU to Modbus TCP. The EMS then sends bare Modbus RTU frames over the TCP connection. Leave it off for a Modbus gateway.

EP E300

What you need:

  • EP E300 converter (e.g. RS485 TO ETH)
  • 24V power supply
  • UTP (Ethernet) cable
  • RS485 cabling (twisted pair)
The EP E300 converter in its two mounting options: guide rail type on a 35 mm DIN rail, and ear hanging type with mounting brackets.

Sollae

What you need:

  • Sollae converter (e.g. RS485 TO ETH (B))
  • 5V power supply (if needed)
  • UTP (Ethernet) cable
  • RS485 cabling (twisted pair)
  • Spfinder (software)
The Sollae converter, a small black box with an Ethernet port, a DC 5V power socket and status LEDs for power, run, link and data traffic.

Waveshare

What you need:

  • Waveshare converter (e.g. RS485 TO ETH (B))
  • 24V/12V power supply (if needed)
  • UTP (Ethernet) cable
  • RS485 cabling (twisted pair)
The Waveshare RS232/485 TO ETH converter seen from above. On the left are the RS232 port and the green RS485 terminal with A+, B− and earth, at the top the LEDs for power, run and RS232 and RS485 data traffic, and on the right the power terminal and power socket for 5 to 36 V DC, the Ethernet port and the Reload button.