Signal-Loss Timeout
When communication between the wireless remote control and the receiver is broken, the receiver stopping movement by itself if it receives no command within a certain time. The time is kept short so that no uncontrolled movement occurs. On the AXI HCT400 this time is 250 ms; when no command arrives, the system goes into safe mode.
In a wireless system the real risk is not the remote control failing but it going silent: the battery runs out, the operator moves out of range, a metal obstacle comes in between. A receiver with no timeout keeps applying the last command it received and the hydraulic lever stays open.
- Heartbeat logic: the remote control sends packets at regular intervals; the receiver resets its counter at every packet. If the counter reaches the threshold, communication is considered lost.
- Choosing the time: too long means uncontrolled movement; too short leads to needless interruption on momentary interference. An order of 250 ms balances these two risks.
- Afterwards: on timeout the motor stops and the system is brought to a safe position; when the remote control comes back, movement does not resume by itself.
This protection is the complement of the emergency stop button. The emergency stop covers the danger the operator notices; the timeout covers the situation in which the operator cannot intervene. On the HCT400 and HCT402, communication is carried out over the XRF encrypted protocol specific to AXI.
The context where this term is used: Converting a tractor hydraulic lever to electronic control