Safety relay system

A safety relay system for acquiring safety input indicating a safety state of a work area from one or more safety components, verifying the safety state based on (i) said safety input and (ii) an operation state of (a) said safety component or (b) at least one additional input unit, and if the safety state is verified, outputting safety output for opening/closing a safety relay to enable an external connected machine connected to the safety relay to operate and on the other hand, if it is determined that the safety state is not verified, opening/closing the safety relay to directly or indirectly stop the operation of at least a hazardous part in the external connected machine, said safety relay system comprising:

• one or more additional input units each for verifying the safety state based on (i) the safety input from the safety component connected thereto, and (ii) the operation state of the (a) safety component or (b) the respective additional input unit, and generating new safety input, the new safety input indicating a safety state based on whether the safety state can be verified and sending new safety input as safety information, wherein said safety information is generated at least in part based on the new safety input;
• a master unit for receiving the new safety input as the safety information from said additional input unit and providing safety output to operate the safety relay based on the new safety input;
• a duplex safety information line for transferring safety information between said units;
• a non-safety information line for transferring the information, which the additional input unit used to check the safety state, as non-safety information separate from the safety input that the master unit received, the non-safety information comprising information concerning the operation state of each safety component or each additional input unit, the non-safety information, line being separately provided from the safety information line, the non-safety information including at least any one or more of
• a. ON/OFF information of the safety component connected to the master unit or additional input unit,
• b. error state or error information of each unit,
• c. output information of the master unit or additional input unit,
• d. operation mode information of each additional input unit,
• e. setup information of each unit, and
• f. input state information in a state in which the safety input of the safety component is omitted;
• and
• a non-safety information output section for outputting the non-safety information transferred on said non-safety information line,
• wherein the one or more additional input units are configured to be connected to at least one other additional input unit, and when the other additional input unit is connected to the one or more additional input units, the one or more additional input units verifies the safety input generated by the connected other additional input unit and generates new safety input based on the safety input from the at least one other additional input unit and the safety input from the component connected to the one or more additional input units and the new safety input indicating a safety state based on whether the safety state of the connected other additional input unit can be verified.