Loss of Communication
The interruption of the valid data flow between transmitter and receiver. Under IEC 62745 this condition is treated as a dangerous failure and the system is expected to go to the safe state automatically; the cause of the loss may be range, interference, battery or a hardware fault.
Loss of communication is the fundamental risk that separates a wireless remote control from a wired one. On a wired pendant, if the line breaks the normally closed contact opens and the machine stops; with wireless the break is invisible and is perceived only as silence. That is why the standard requires silence to be treated as a fault and to bring about a stop.
The most frequent causes in practice:
- The battery voltage dropping and the transmitter output power weakening.
- The receiver antenna being left inside a metal enclosure, or the antenna cable being damaged.
- The proximity of broadband noise sources such as inverters and welding machines.
- The operator moving behind a concrete wall or steel structure.
The expected behaviour at the moment of loss is that all motion outputs are released and that motion does not restart of its own accord when the link returns. For complaints of intermittent response, work through the battery first, then the antenna placement, and lastly the interference source; this order is the fastest route to a diagnosis.
Context in which this term is used: Wireless Crane Remote Control Selection Guide