What is pairing (learning), and do two remote controls on the same site interfere with each other?
Learning makes the receiver respond only to its own transmitter's identity. The real limit on site is not the identity count but the shared channel.
Pairing is the learning operation that makes the receiver respond only to the identity of one particular transmitter. A packet from a remote control that has not been taught is quietly discarded by the receiver, so more than one set can work on the same site. What sets the limit is not the number of identities but the number of transmitters filling the shared channel at the same time.
What learning guarantees
In the learning procedure the receiver is put into learning mode for a short period, a packet is sent from the remote control, and the receiver writes that identity into its memory. After this, pressing a button on another remote control triggers no output at all. On AXI's SF series this is done with the learning procedure described in the manual; on the HCT402 pairing requires being within 50 m, while the operating range is 100 m. How the identity is protected matters too: the difference between fixed code and rolling code decides the resistance to copying.
There is a trap in the other direction as well. If more than one receiver on the site is powered and listening during the learning, both of them can learn the same remote control. The result comes back months later as the complaint "this remote control moves the crane next door as well". Always carry out the learning with only the target receiver powered.
What to watch when several sets are used on the same site
- Make sure each receiver has learned only its own remote control; if two remotes have been taught by mistake, the receiver responds to both.
- If you use a spare remote control, record which receivers it is defined in; in a multiple transmitters, single receiver arrangement that list is the only reliable source.
- When a conflict occurs, clearing the learning memory and teaching again is the fastest fix. Clearing the memory deletes all the identities; bear in mind that you will also have to teach the spare remote control defined in that receiver again.
- If a large number of sets are transmitting continuously, the problem is not an identity conflict but channel occupancy; in that case latency and retries increase.
Symptom, real cause, remedy
| Symptom | Real cause | Remedy |
|---|---|---|
| Another machine's remote control moves ours as well | Two remotes taught to the same receiver | Clear the memory and teach only the correct remote control |
| Commands are delayed and drop out in between | Channel occupancy | Reduce the number of sets transmitting continuously, move to a hopping system |
| The spare remote control does not work on some machines | No record was kept of what was taught | List which receiver it is defined in and teach the missing ones |
| The pairing simply will not hold | The learning distance has been exceeded | Move closer to the receiver; on the HCT402 learning is done within 50 m |
What learning does not solve: channel occupancy
Separating identities and channel occupancy are two different subjects. Even if the receiver discards foreign packets, those packets occupy the air; as the number of transmitters grows, the chance of each command getting through on the first attempt falls. At this point teaching again changes nothing. Frequency hopping systems spread the transmission over many channels and so behave more steadily in the same environment. The habit of holding a button down throughout the shift also increases the occupancy; teaching operators to cut out unnecessary transmission gives a measurable benefit.
Make acceptance testing a habit on a new installation: press each remote control on the site in turn and verify that only its own machine moves. Do the test with the machines unloaded and record the result in writing. This list, showing which remote control is defined in which receiver, becomes your starting point when the complaint "the remote controls have got mixed up" comes in later. As the site grows, keeping the list up to date is far less work than repeated rounds of re-teaching.
The full topic: Receiver-transmitter pairing procedure