The SerialGuard AnalytICS Platform is designed to monitor legacy serial communications in industrial control systems (ICS) and operational technology (OT) environments. The platform addresses security gaps in legacy assets that use serial connectivity protocols such as RS-232, RS-485, and RS-422 interfaces, along with protocols like Modbus, DNP3, IEC101, Profinet, and BACnet MS/TP. The platform provides passive monitoring of data transmitted between Field Controllers and Field Devices in ICS environments. This monitoring approach maintains the integrity of communications while providing visibility into device behavior. The system is designed to detect anomalous communications that may indicate malicious data or unauthorized controller change attempts. The platform addresses the security challenges created by IT/OT convergence, where previously isolated OT networks are connected to modern IT networks. Legacy serial protocols were developed before the internet era without security considerations, making them vulnerable to spoofing, man-in-the-middle, and false feedback attacks. The SerialGuard AnalytICS Platform enables organizations to implement continuous monitoring programs for legacy assets in critical infrastructure sectors including electricity, oil, gas, water, nuclear, and transportation. The platform provides real-time visibility into serial communications, allowing operators to detect unauthorized controller changes and anomalous behavior regardless of what proxy systems like converters and gateways may represent.