Optics counters won't zero

[meik84]

Maybe I'm doing something wrong, but CMC's optics counters (N91) won't zero after an SPS burn. They do change when you move the optics manually (N91's values don't match with the mechanical counters, though), but they don't get zeroed when you put the OPTICS ZERO switch to ZERO. They do drive to the zero position mechanically, however. Suggestions?

 

[MrFickles]

Give this a try

Found this buried in the Apollo 15 flightpalan

Optics ZERO - OFF
Optics PWR - OFF then ON
Optics shaft and trunion - move to <10° manually
Optics ZERO - ZERO

This was labeled as "OPTICS CAL PROCEDURE"

 

[meik84]

Seems to be a CMC problem. Pulling the COMPUTER cbs and resetting them (i.e. forcing a hardware restart) solves the problem. Software bug?

 

[Thymo]

I don't have time to test this today. I'll take a look if I can reproduce it tomorrow.

Maybe the zero switch doesn't trigger a zeroing of the CDUs

 

[indy91]

I've had this happen a small number of times. It definitely breaks something in the AGC, probably some flag, but I'm not sure if the cause is really a software bug. Probably something wrong with our optics code, not sure what.

 

[meik84]

Easiest way for now to clear this seems to be like this:
- select P06, put CMC to standby and back on
- set DRIFT & REFSMMAT flag again (P06 seems to clear them)
Cautious people may also do a CMC clock update, uplink new SVs and run a P52 after that. Not that you'd need it...

 

[Thymo]

I've done some testing yesterday using Artemis072.
I triggered the gyro test outside of P40 (using an EMP) and found that unless you go back to P00 (other MMs should work too but haven't tested) channel 12 which (among others) controls the OCDUs is not reset so TVC control will remain active.

If you encounter this again after a P40 please do a V01N10E 12E to display the value of chan 12 and post the contents of R1 here.
Then doing a V37 to P00 should make everything work again.
I'll do some more digging to determine if this is a bug in NASSP or in the AGC code.

Cautious people may also do a CMC clock update, uplink new SVs and run a P52 after that. Not that you'd need it...

That's completely unnecessary. The only time you'll need a clock update is after staying in standby for more than 23 hours. After that the SCALER will overflow and the computer won't know how much time was spent in standby.
To remedy this, one has to briefly put the computer to operate and back to standby before those 23 hours.

You don't need an extra state vector update. You'll only need one if you'd been getting one anyway regardless of being in standby or not. OR if you do a maneuver without the AGC monitoring the velocity changes, but that would also be the case if you did that with the AGC running and forgetting to run a thrusting program.

P52 is also not needed since you don't change anything to the IMU during standby. Sure you can do one to get rid of drift, but we don't simulate that anyway (as of yet). Right now the only 'useful' reason to do a P52 in NASSP is to align to a new REFSMMAT.

 

[meik84]

If you encounter this again after a P40 please do a V01N10E 12E to display the value of chan 12 and post the contents of R1 here.

00040. Interestingly, bits 4 and 5 in channel 33 are displayed correctly and change in the right way when I throw the ZERO and MODE switches. V37E00E doesn't help. Even V36 doesn't.
And no, I don't belong those over-cautious people... Only thing I did was runing P52 to see if the optics work properly after my troubleshooting; they do.

 

[indy91]

00040. Interestingly, bits 4 and 5 in channel 33 are displayed correctly and change in the right way when I throw the ZERO and MODE switches. V37E00E doesn't help. Even V36 doesn't.
And no, I don't belong those over-cautious people... Only thing I did was runing P52 to see if the optics work properly after my troubleshooting; they do.

Can the CMC drive the optics properly even if it can't null the optics registers anymore?

 

[meik84]

It drives them, yes. But it's no use, as CMC's counters and real position don't match. Auto optics point everywhere, but not at the star; if you do it manually you get a N05 that's beyond good and evil.