To relieve a bit of lockdown boredom I thought I'd try a Draytek USB temperature sensor on my AP903 in the garage, having never played with one before.

Comparison with an old-fashioned Factory Thermometer suggests that the sensor as supplied is a couple of degrees out, but that can be compensated for in the AP903 settings.

Of slightly more concern is that every twelve hours or so the sensor shows a sudden temperature spike from ambient to 200C. (well OK, the last one was only to 199C)

It's probably just as well that I can't get the email alert setting to work...... :mrgreen:

Quite impressive! ... even more so, because the sensor used (the LM75) can't actually o/p those values

(Theoretically, it could o/p ±128°C, but it limits itself to -55°C to +125°C. Accuracy overall is a not-to-get-too-excited-about ±3°C)

LM75 Datasheet: http://esd.cs.ucr.edu/labs/temperature/LM75.pdf

If you have this device plugged into a 'USB extension lead', you could try a different (shorter?) one ... it could be electrical noise pickup. Even so, the Draytek software should be filtering out such drivel

I tried it initially just plugged straight into the USB socket, but then I thought that the heat from the AP903 would affect the readings so I used the USB cable supplied with the sensor. I get the same behaviour in both cases - on a roughly 12 hour cycle (eg around 2100 last night and shortly after 8.30 this morning) there is a spike to 199C. Odd.

Still doing it -

Have you tried it with any of your other AP903's ... if there's something wrong with the sensor, or Draytek's programming, you'd expect them all to exhibit the same effect.

I shall try that this weekend and report...