SX-IO — Serial Port Passthrough

Overview

Serial Port Passthrough lets you tunnel the SMX-RNS20’s physical RS-232 or RS-485 port to a virtual COM port on your engineering PC. Any serial-based programming tool (e.g., a PLC programmer that uses COM ports, a terminal emulator) can then talk to the remote serial device as if directly connected.

Machine-Side Setup

• Connect the serial device (PLC, drive, instrument) to the SMX-RNS20’s RS-232 or RS-485 port using the appropriate cable.
• Log in to the SMX-RNS20 web interface → SX-IO → Serial Port.
• Configure the serial parameters: baud rate, data bits, parity, stop bits, flow control. These must match the connected device.
• Enable Serial Passthrough mode (as opposed to Modbus RTU master mode).
• Save the configuration.

Engineering PC Setup

1. Connect to the SMX-RNS20 via SX-Client.
2. In SX-Client, locate the device’s Serial Port service in the forwarded ports list.
3. A virtual COM port will be available on your PC (shown in Device Manager). Note the COM port number.
4. Open your serial application (TIA Portal, STEP 7 with MPI-to-TCP adapter, HyperTerminal, etc.) and select the assigned virtual COM port.
5. Communicate with the remote device at the configured baud rate as if directly connected.

Screenshots — SX-IO Serial Port Configuration

Step 1 — Modules → Driver

Step 2 — Add new driver

Step 3 — Driver settings: Name, Endpoint (port=0 upper USB / port=1 lower), Type = SERIAL PORT

Step 4 — Save driver

Step 5 — Status → Driver: connection confirmed

Step 6 — Modules → Tag

Step 7 — Tag configuration

Step 8 — Save tag

Step 9 — Status → Tag: live data from serial device