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watchdog timer errors when use C1 C2 for several minute


smile Apr 24, 2026 07:43 AM

Hi to All,

I'm noticing a CR800 os32.07 that if I hold ON port C1 or C2 for several minutes, which activate two relays via a power circuit, watchdog timer errors are generated and the logger resets.

This doesn't happen when the relays are activated for much shorter times. Does anyone have experience? Thanks.

Smile


JDavis Apr 27, 2026 05:02 PM

Have the data logger measure the battery voltage during that time. I suspect the power system is being loaded down too much.


smile Apr 29, 2026 08:27 PM

Thanks for the suggestion, but I'm sure the battery and power supply are OK. I have a question, though, because I noticed that the C1 or C2 port drops to 4V during the ON phase. Is it possible that the power circuit that controls the relay is drawing too much current? Could this cause these errors? Thanks.


JDavis Apr 30, 2026 03:30 PM

You could run the same program on a CR800 without the relays connected, and see if there is a watchdog error holding the C ports high an extended period. 

The output on the C port is running through a pullup resistor. The actual voltage you measure depends on how much current it is loaded down with. Short circuiting a C channel to ground does not cause a watchdog, because the pullup resistor limits maximum current out through the channel. You could check the voltage on the 5V terminal. It shoudl stay over 4.5V.


smile May 2, 2026 07:06 AM

Great suggestion, I'll try it next time I go to the site. Thanks.

Smile

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