Simattachment AS803 clock volts display

[MSFS 2024] Bug Reports Aircraft
1

There are a few aircraft in the sim that appear to use the AS803 simattachment - the C172 Classic, the DV20, and the P51 are three that I’ve found.

Of those three, the C172 shows the correct voltage, the DV20 does NOT show the correct voltage (it reads 0.0 volts) and the P51 shows the correct voltage.

However, both the C172 and the DV20 are using the newer 2024 electrical system, while the P51 is using the older 2020 electrical system.

I’ve dug into the simattachment’s files, and the AS803 is using the preexisting M803 javascript code, where it is looks to be reading it’s voltage information from ELECTRICAL MAIN BUS VOLTAGE. This makes sense, and would explain why it works in the P51, using the older electrical system, and why it does not work in the DV20, which uses the newer electrical system.

However… I cannot figure out why it works in the C172. The C172 uses the newer electrical system, and I can tell through the simvar watcher that ELECTRICAL MAIN BUS VOLTAGE remains zero while the aircraft is running. There are no extra behaviour parameters being sent to the simattachment that would set a different bus to read voltage from, nor would the m803 javascript file be able to read those.

Since the behavior xml file for the C172 is encypted (unfortunately), as is it’s systems.cfg file, I cannot tell if there’s something else going on. It’s obvious that since the ELECTRICAL MAIN BUS VOLTAGE is still reading zero, that there’s nothing being written to that simvar (which shows as writable in the SDK, even though it’s not).

As this is a bug in the DV20, as well as a stumbling block for developers to use this otherwise great simattachment in aircraft that utilize the up to date electrical system, could someone from Asobo please check this out? It would be great if the method that the C172 is using to display the voltage on this simattachment could be shared.

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Hello @JimStewart,

The M803 expect the ELECTRICAL MAIN BUS VOLTAGE or in this case : ELECTRICAL BATTERY VOLTAGE

Can you test with this in your panel.xml :

<PlaneHTMLConfig>
    <Instrument id="M803">
        <Name>M803</Name>
        <VoltageValue>
            <Simvar name="ELECTRICAL BATTERY VOLTAGE:'main_battery'_n" unit="volts" />
        </VoltageValue>
    </Instrument>
</PlaneHTMLConfig>

parsecd_6J01YlaZzJ
parsecd_6J01YlaZzJ1920×933 113 KB

Let me know if it’s working please.

Regards,
Boris

3

Hi Boris, that did not work

I’ve added your recommended lines in the panel.xml, and adjusted to match my battery name. I also then tried ELECTRCAL BUS VOLTAGE and the name of my main bus, as well as forgoing names and using the index, just in case.

However, I also note that in your screenshot above, based on the views of the debug window you’re showing, it looks like you’re using an aircraft with an older, 2020-style electrical system. Perhaps I’m wrong, but the debug window when using the most up-to-date electrical system looks like such:

image
image1561×839 132 KB

As I had mentioned, there doesn’t seem to be an issue when an aircraft using the older 2020 electrical system is using the sim attachment (as in the Asobo P51).

However, my aircraft is using the up-to-date newest system.

Since the 803 voltage readout doesn’t work in the DV20 (up-to-date electrical), but DOES work in the C172 (also up-to-date electrical), there must be a method to use it. Is it possible to look at the C172 and see why it’s working there? Our ability to browse the C172 Classic files via the VFS projector is limited, since most are encrypted.

4

Hello @JimStewart

You’re right, I got mixed up sorry.

I ran the same test in the DA62 from the SDK and it works as expected.
I only added the the code I mentioned above in the panel.xml (common).

There is no additional configuration in the C172.
Check that the avionics bus is connected.

image
image1920×723 124 KB

Regards,
Boris

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5

Hi Boris. You’ve provided the missing link. I had added the instrument config to the panel.xml that was in the panel folder in my function interior attachment. Adding it to a panel.xml in the common folder allowed it to work as expected.

All good from my dev viewpoint now concerning my own use of the instrument, however you may want to use the bug report to mark that the same fix may be needed for the dv20 that’s in the sim (I can’t tell for sure because that aircraft also has encrypted files).

Also, it could be very useful for the Sim Attachments section in the SDK documentation to mention any needed panel.xml entries for the various attachments. In addition, I noted that on this particular instrument, the behavior parameter list didn’t show anything, while there is a usable parameter to link a potentiometer to this gauge. As many of the sim attachment behavior parameter sections are blank, I suspect there’s more that just this attachment missing details.

6

Hello @JimStewart,

Glad to know it’s now working :slight_smile:

This should be reported on the forums (if it hasn’t been already) or through the MSFS Zendesk, as it will then go through the proper channels.

I agree. This is a work in progress. The documentation will be updated.

Thank you,

Regards,
Boris

7

Regarding the DV20, the report on the forums already exists: Diamond DV20: No Voltage & Electrical Warning Light on when Power is Available - Aircraft & Systems - Microsoft Flight Simulator Forums

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