cellular - PLC Programming & Automation

Remote PLC Monitoring and Control Without Open Ports

September 12, 2026January 20, 2024 by PLC

Ladder rung for a remote write permissive: XIC on Remote_Session in series with XIO on the Local_Only key switch and XIO on WDog_Fault, driving the Remote_Write_OK coil

Remote access to a PLC that security will sign off: outbound VPN routers, read-only web HMI, an access rights table, a permissive rung and an audit trail.

Wireless PLC Communication: Wi-Fi, Radios and Cellular

September 13, 2026January 4, 1970 by PLC

Timing chart of a wireless link: the radio link drops, I/O data stops arriving, the connection fault bit sets after the timeout window expires, the line stops, and everything recovers only after the link returns and the logic is reset

Wireless PLC communication done properly: choosing Wi-Fi, 900 MHz radios or cellular, RPI and timeout budgets, antennas, roaming, and link loss logic.