What is the difference between a passive stop and an active stop?
A passive stop is the stop that occurs by itself when the transmitter's broadcast is interrupted (battery flat, device switched off, out of range). An active stop is the automatic stop the base station initiates itself upon not detecting a valid signal; the time depends on the manufacturer's declaration and on the risk assessment for the machine, and is expected not to exceed approximately 0.5 seconds.
Both ultimately stop the machine, but what triggers them and their timing are different.
A passive stop is not a decision but a consequence. The transmitter goes silent, the receiver stops getting valid commands, and the outputs are released. Its source is on the remote control side: a flat battery, the device being switched off, going out of range, the device being dropped and failing.
An active stop, on the other hand, is a deliberate action on the receiver side. If the base station does not detect a valid signal within the defined time window, it initiates the stop function itself. This time is a parameter declared by the manufacturer; the risk assessment for the machine determines it, and in wireless remote control applications it is expected not to exceed approximately 0.5 seconds.
Its meaning in practice is this: a passive stop alone is not sufficient, because it covers only the case of the broadcast being interrupted. If the signal is arriving but arriving corrupted, if a locked-up command is being repeated, or if communication is partly degraded, the passive stop does not come into play. The active stop closes this gap; if there is no valid and refreshed signal, the movement is released.
These are general standard approaches. Confirm from the user manual which mechanism a particular set implements and in what time, and additionally keep a hard-wired emergency stop on the machine side.
The full topic: Wireless remote control installation: pairing, relays, safety