What happens if the PLC stops?
As with every usual hardware PLC also, the I/O system used determines how the outputs behave: Beckhoff I/O features watchdogs for control of the bus nodes to ensure that they assume a failsafe state. Nevertheless, for every programmable controller involving software intervention (i.e. for PLCs just as much as for PCs), it is important to ensure that functions that are relevant to safety be safeguarded with independent facilities that conform to the usual technical specifications (emergency stop and access control).
