Definitions of Watch Dog and Inhibit

A watchdog circuit is a circuit that monitors the output, counting pulses, and if the pulses stop, or if the output becomes unexpected in anyway, then the watchdog resets the circuit (microprocessor typically) Think of it as keeping the processor sane, or in synch with dependent operations.

I think Inhibit may simply be holding down (or up) the voltage on an output for a period of time, so that the other parts of the circuit can complete its operation. When the period is done, then pulses can continue.

I also have another definition.

Watch Dog provides an alarm functions in an electronic system (PLCs, computer, etc) to warn the operator a major failure has or may occur.

It monitors the status of different critical components (hardware and/or software) used by the system and trigger an output to warn the operator. This wired output can either be open collector or relay type.

Inhibit would mean "stopping" a certain function carried by the system so that it becomes trasnparent for the system.

For example default system settings will raise certain alarm under different circumstances. In your particular context some of these alarms (not critical) are not interesting. You inhibit these alarm messages so that they do not appear.

In computer/ control environments there are time-dependent steps. Watchdog checks if the next event comes inside the predefined time frame. It the event delays the watchdog generates an error signal.

An example: in the old DEC PDP computers watchdog supervised the response time of peripherals. Too long response time induced an error signal and finally an error message for the operator.

In IBM mainframe parallel channel environment during the initial selection of external devices also a watchdog checked if the selection was finished in 10μsec.

Inhibit: if you force to block an event when all of the normal initiating conditions are set.