A kind of PLC Hostlink order filter methods and device based on RS232 communications protocol

The present invention provides a kind of PLC Hostlink order filter methods and device based on RS232 communications protocol, it is possible to increase PLC tackles the ability of network attack.Methods described includes：According to initialized Hostlink command library, chained command filtering item is set, and generates chained command filtering rule storehouse；Intercept host computer and be sent to PLC packet, and the packet of interception is parsed, identification code is extracted；The identification code of extraction is matched with the chained command filtering rule storehouse generated, if there is occurrence, the packet is filtered, otherwise, then the packet of interception is sent to PLC.The applicable industrial control system field of information security technology of the present invention.