Is an emergency stop given over the wireless remote control enough?
No. In the general approach to machine safety, a stop command sent over a wireless link does not automatically replace the fixed, hard-wired emergency stop device on the machine in the sense of ISO 13850. The machine is also expected to have a manually reset, latching red mushroom-head button; wireless stopping complements it, it does not substitute for it.
A wireless channel is, by definition, a channel that can be interrupted. The battery runs out, the device goes out of range, strong interference appears in the environment. For that reason, wireless stopping is treated as an additional layer in the safety architecture.
The general expectations are as follows:
- The machine has an emergency stop device compliant with ISO 13850: a red mushroom-head button on a yellow background, manually reset, latching, and requiring a deliberate reset.
- IEC/EN 62745 covers, for cableless control systems, the behaviour on establishing, indicating and losing communication as well as the behaviour on loss of supply; loss of communication counts as a dangerous failure and the system is expected to go to a safe state.
- EN IEC 60204-32 covers control circuits, interlocks and emergency stop requirements for hoisting machines.
- An emergency stop function can only be Stop Category 0 or 1 in the sense of IEC 60204-1.
This is general standards knowledge; the conformity of a specific product with these standards can only be confirmed from the manufacturer's declaration of conformity and the user manual. The product records for the AXI ST/SF sets do not state an emergency stop button or an emergency stop function; do not assume such a function exists. In all cases, build the safety function through the machine's own hard-wired emergency stop circuit and confirm the set's features from the user manual.
The full topic: Wireless remote control installation: pairing, relays, safety