Cradlepoint MC20-SRL RS-232 Serial Expansion Module for S400 and S450

The Cradlepoint MC20-SRL solves one of the most common problems in industrial connectivity: valuable equipment that still speaks RS-232. Installed in the MC20 expansion slot of an S400 or S450 IoT router, the module adds a standard DB9 serial connector, allowing the router to communicate directly with PLCs, utility meters, weigh scales, environmental monitors, and other controllers that predate Ethernet. Without a serial port on the router, connecting such equipment means an external serial-to-IP converter—another device to power, secure, configure, and eventually replace. The MC20-SRL removes that layer entirely. Serial data terminates on the router itself, transits the cellular WAN under the router's security policies, and the whole site remains one managed device in NetCloud. For OEMs and integrators building repeatable site kits, that consolidation simplifies both the bill of materials and long-term support. Typical deployments include utility submetering, where meters report over RS-232; retrofit SCADA outstations reading legacy RTUs; and retail or logistics sites with serial scales and printers. The module ships at roughly 0.15 lb and installs or swaps in the field. It is one of three MC20 options for the S-series platform—alongside the MC20-ETH dual Ethernet module and the MC20-GPO GPIO module—so a standardized S400/S450 fleet can be tailored per site with a single slot decision.