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Discussion: Many duplicate punches using activated SIAC

in: Orienteering; Gear & Toys

Mar 30, 2023 2:12 PM # 
Since SI gripe season is now officially open maybe it's time to puzzle jSh with another mystery from a few months back. We have been seeing with some SIAC's with air mode activated and controls in beacon mode that when the stick comes into range of a control, instead of the usual feedback of multiple beep/flash, there is just a single beep/flash with the beep being very faint. Faint enough to be missed or uncertain and the user punching again to make sure a punch was registered. At download the printout then shows many duplicate punches, far more than the additional punch attempts and at more controls than those re-punched even.

This happened with several SIAC sticks which led to wondering about battery status, yet all affected sticks tested in the acceptable range. The common theme between them though was that they were by now several years old.

Perhaps it's time to service or replace sticks exhibiting this behavior but still one wonders what causes this when the battery check shows the battery in the acceptable range.
Mar 30, 2023 2:33 PM # 
fossil, this is an easy one (and your username checks out, grin :D)

These SIACs most definitely have an old battery. Old, but not necessarily often-used, batteries become "lazy", a process called "passivation". Check for more details. In SIACs, the effect is that while the initial feedback at CLR and CHK may work (partially supported by a relatively large capacitor supporting the battery), later punch feedback at controls can not be sustained by the battery and therefore the SIAC enters a "loop of death":
10: SIAC enters and senses AIR+ field at control
20: SIAC writes punch to internal memory
30: SIAC starts feedback, but voltage drops badly and the electronics go into a so-called "brownout", feedback stops
40: SIAC battery voltage recovers a bit, a "watchdog-reset" happens, the SIAC "reboots back alive".
50: GOTO 10

This loop rapidly fills up punch space. On download, if the competition software is restricted to reading, say, the first 64 punches, this SIAC can even be claimed to have missing punches at the end of the course. If the software has a license model that allows more than 64 punches only on premium licenses and locks up if more punches are read from any chip, this SIAC might result in a "denial of service attack", locking down the software for any further use. No no, of course this never happened, and additionally it's been fixed long ago, would you please look at this shiny gadget called a neuralyzer for me?

If, in other software, such mispunch verdicts do still happen, a download in SI-Config+ will often show the missing punches.

The passivation problem on old SIACs was identified as an aging factor separate from voltage drop due to heavy use and checked by the "battery test" station, therefore the relatively recent addition of the "change every 3, max. 4 years"-statement from SI.

TL,DR; please have the batteries on those SIACs replaced ASAP.
Mar 30, 2023 7:56 PM # 
This happened to my SIAC a little over a year ago. At that stage I'd had the stick well over six years.
Mar 30, 2023 11:02 PM # 
Ah, mystery solved! I have one of the SIACs fossil is referring to - the battery is nearly six years old and it is little-used, including going ~3 years without any use at all immediately prior to the problem starting. I did observe normal multiple beeps/flashes at clear and check, with the single beep/abbreviated flashes at controls.

So it sounds like if the battery is only expected to last 3-4 years regardless, there's no reason not to use the SIAC all the time. (Somewhere I saw numbers on what SI considers normal usage and it's way more punching than I do so it doesn't seem like I'd run the battery down faster than that from use.)

As a side note, it seems like different download software has different behavior with respect to handling the multiple punches, at least in terms of what appears on the splits printout. The first time the multipunch thing happened was at two events in Ottawa - the MeOS printed showed 1-4 punches within 1-2s for every control. Using the same SIAC for three events two weeks later, the printout (from SI's software) had only a single punch for every control but the last and two for the last. I think the ~4 punches per control that MeOS showed is probably about what the stick is actually recording since it didn't fill up with 24 controls. However, the stick filling up is an even bigger problem if some software can't read more than 64 punches...

This discussion thread is closed.