Control system for surgical robot system with safety device

A method of selectively filtering communications to and/or from a main controller of a surgical robot system, the surgical robot system comprising a surgical robot, the surgical robot comprising a base, and an arm extending from the base to an attachment for an instrument, the arm comprising a plurality of joints whereby the configuration of the arm can be altered, and an electrosurgical instrument attached to the arm at the attachment for an instrument, the main controller configured to receive communications identifying inputs from an operator of the surgical robot, generate control signals for energising the electrosurgical instrument based on the inputs, and send communications to the surgical robot identifying the control signals for energising the electrosurgical instrument, the method comprising:

• receiving at a safety device a communication to or from the main controller;
• determining whether at least one filter criteria has been specified;
• in response to determining that at least one filter criteria has been specified, comparing the received communication to the at least one specified filter criteria;
• in response to determining that the received communication matches at least one of the at least one filter criteria, rejecting the receiving communication;
• and
• in response to determining that the received communication does not match any of the at least one filter criteria, outputting the communication to the relevant device.