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AX2500/2850 Motor Controller User’s Manual 79
Reception Watchdog
For best results, reliability and safety, the controller will also perform a series of correc-
tions, adjustments, and checks to the R/C commands, as described in the following sec-
tions.
Reception Watchdog
Immediately after it is powered on, if in the R/C mode, the controller is ready to receive
pulses from the R/C radio and move the motors accordingly.
If no pulses are present, the motors are disabled, and the controller’s display will scroll
alternatively the letters “no ctrl” as shown in Figure 51 below.
After powering on the R/C radio receiver and transmitter, and if the wiring is correct, the
controller will start receiving pulses. For a preset amount of time, the controller will moni-
tor the pulse train to make sure that they are regular and therefore genuine R/C radio com-
mand pulses. After that, the motors are enabled and the LEDs will display a pattern related
to the actual motor direction (see Figure , “Motor Direction Status,” on page 66).
This power-on Watchdog feature prevents the controller from becoming active from para-
site pulses and from moving the motors erratically as a result.
Similarly, if the pulse train is lost while the motors were enabled, the controller will wait a
short preset amount of time before it disables the motors. If the pulses reappear during
that time, the controller continues without any breaks. If the communication is confirmed
lost, the “no ctrl” message is displayed again.
Note: the Accessory Outputs C and D will be turned Off when radio is lost.
Important Notice about PCM Radios
PCM radios have their own watchdog circuitry and will output a signal (normally a
“safe condition” value) when radio communication is lost. This signal will be inter-
preted by the AX2500/2850 as a valid command and the controller will remain active.
To benefit from the AX2500/2850’s radio detection function, you will need to disable
the your PCM radio watchdog.
R/C Transmitter/Receiver Quality Considerations
As discussed earlier in this chapter, the AX2500/2850 will capture the R/C’s command
pulses with great accuracy. It will therefore be able to take advantage of the more precise
joysticks and timings that can be found in higher quality R/C radio, if such added precision
is desired in your application.
FIGURE 51. “No control” message will scroll when no valid radio signal is present