XBL-C21A

Description

Single-port RS-232C communication module for XGB family PLCs. Acts as an RS-232 client/server, supports XGT protocol and Modbus ASCII/RTU, and can be used with an external modem for remote connections.

The Polar Energy Assessment:

The XBL-C21A is a compact serial interface module that provides one RS-232C port (DB-9 female) for program download, remote control, or device-level communications. It supports multiple operation modes (P2P, client/server), XGT dedicated protocol and Modbus ASCII/RTU, and standard serial settings (data bits, parity, stop bits, up to 115200 bps), making it suitable for legacy device integration and remote modem links via an external modem. Use it when you need a simple, robust RS-232 channel on an XGB PLC.

Pros

• Simple RS-232 port for legacy devices and modem links.
• Supports both XGT and Modbus (ASCII/RTU) protocols for interoperable communications.
• Small footprint and low integration hassle on XGB racks.

Limitations

• Single serial port only; not suitable if you need RS-485 multi-drop or multiple serial channels.
• RS-232 distance and noise limits mean it’s not ideal for long runs without converters.

Typical use cases

• Connecting an HMI, barcode reader, or legacy instrument via RS-232.
• Remote program downloads or modem-based remote access when paired with an external modem.