Serial Bridge for Tridium Niagara

Serial Bridge connects Tridium Niagara serial drivers to serial devices however they are reached. It creates virtual COM ports that communicate over TCP/IP instead of physical serial cables, and on a Windows Supervisor it also opens the computer’s own COM ports, including USB-to-serial adapters. Any Niagara serial driver can use either kind of port — for example, the Apogee P1 driver for Siemens RS-485 field devices, the Johnson N2 driver for Metasys N2 buses, or the SMI driver for window and blind actuators. Serial Bridge was formerly called Virtual Serial Port.

Virtual ports solve common integration challenges that arise in modern building automation. Supervisors, virtual machines, and cloud-hosted Niagara deployments have no serial ports that Niagara drivers can use, making serial communication impossible without this module. JACE controllers have a limited number of serial ports, and virtual ports allow expanding beyond that limit by adding serial-to-Ethernet gateways. RS-232 cables are restricted to short distances, but a gateway at the device end and a virtual port on the Niagara end extend serial communication across the entire IP network.

In retrofit projects, virtual ports eliminate the need to rewire serial buses back to a new controller — gateways can be placed at each existing serial bus instead. Wi-Fi or cellular serial gateways can reach equipment in locations where running cable is impractical, such as rooftops, parking structures, or remote pump stations. A single Supervisor can manage serial devices across multiple sites via VPN, with gateways at each location. Virtual ports also simplify commissioning and troubleshooting by allowing engineers to connect to serial devices over the network without being physically at the panel.

When the devices are next to the Supervisor, no gateway is needed. Plug a USB-to-RS-485 adapter or an optical meter probe into the Windows Supervisor and Serial Bridge lists it under its COM name, ready for any serial driver. The baud rate, parity and flow control set in the driver apply to the port directly, including protocols that change the baud rate during a session, such as IEC 62056-21 meter readout. A USB adapter that is unplugged and plugged back in opens again by itself, without a station restart.

Each virtual port is configured with the IP address and TCP port of the remote serial-to-Ethernet gateway. The module implements the standard Niagara serial port interface, so every port appears as a regular COM port to any serial driver. Ports reconnect automatically on failure, and real-time status shows the state of each port at all times. Serial-to-Ethernet gateways are widely available from manufacturers such as Moxa, Lantronix, Digi, Perle, and others, and Serial Bridge works with any gateway that provides a raw TCP socket connection.