Hi,
If the OMS are firing at the proper TIG time you may know by different ways.
The easiest (check in external view if they are light on
);
More realistic and more flight simulator oriented, look at the Pc% gauges for L and R OMS engines in the OMS/MPS display: if they go up to 100% with a white tape bar they ignited, conversely at cut off they should go back to 0% again.
Alternatively, you can observe the data field in the top-right corner of the OMS xxx MNVR EXEC display (where you get the orbital information) and see if the TGO decreases (time to go, time to cut off) as well as if all DVx,y,z values decreases (if you want to change only DVx than only the DVx field will be not zero and it will start decreasing as the burn progresses, if you wanted to change also other velocity components DVy, DVz, they will be also be not zero at start of burn and showing decreasing values during the burn); as all DV’s displayed are supposed to be interpreted as “velocity to be gained by the burn”) while at cut-off all numerical values will stop changing, they might not be really stop all three at 0.0 … some small RESIDUALS might still be there (something like, +/- 0.x or as high as +/- x.x), in this case sometimes they need to be NULLED (brought to exactly 0.0 nearby, maybe to +/- 0.1 fps) or not, depending on situation and flight plan, in case you need to fire manually the RCS in translational mode to trim the residual speeds, for this you must make sure you get the flight controller switch to ON to can command the RCS jets as required. Lastly, you may also get a clue that the OMS are burning looking at the values of the CUR HA and HP in the same display which should tends towards the target values.
About the OMS ARM, ARM/PRESS, OFF switches on central panel C3: to can ignite the engines they must be on ARM/PRESS (better) or ARM, the difference is that in ARM/PRESS at cut off the system will command an automatic purge of residuals propellants in the fuel lines, in ARM this automatic purge doesn't happen, in OFF the engine cannot be fired or once fired automatically they can be switched off manually at any time you need by bringing these switches to the OFF position from ARM or ARM/PRESS once they were automatically ignited.
About the OMS fuel, the propellant status can be seen on panel O3 above the pilot station putting the knob selector to OMS FUEL or OXID and read out the numbers in the red digital readout (see photo).
At the moment in the OMS/MPS page you mentioned, only the Pc% tape is driven (combustion chamber pressure for left (L) and right (R) OMS engine), the other two tapes: He TK P and N2 TK P have to do with pressurization circuits, not implemented so far, so they are not functional and have no effect on OMS.
About the SPEC 34 display…some nice information can be found in the RENDPROX doc, but how to use it to actually perform a rendezvous in SSV I can’t tell, as I still didn’t figure out by myself (so it would be very instructive to see others help you out with this, and if eventually you manage to do it you will tell / teach me how to do later on
).
Cheers.