Links
File format
Record format
Accessing the file data

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File format  (top)

    The p12mProg is the AO control program for the 12 meter telescope. It records the telescope status once a second to a logfile.
Some properties of the file are:

File location:	/share/phidat/p12m/
daily file creation	new file started each day at 0Hrs AST
file Naming	logdata_yyyymmdd.dat
file size	24Mbytes/day
file format	binary little endian.. see record format below

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Record format  (top)

    The file contains records (86400  if a full day is recorded). each record is:

field	type/ units	byte Offset	description
cpuTmAtWaitTick	double sec1970	0	when we waited for the next 1 sec tick for this record. This is normally 50 millisecs before the tick
cpuTmAtTick	double sec1970	8	Time when we woke up for the tick.. (with fractions of a sec)
durRdDev	double secs	24	the time from the tick, till when we complete the status read from the device. This includes computing the new position, sending it to the ramp logic, and then reading the device status block. It is typically 40 ms (25ms is to actually do the read).
durWrLast	double secs	32	secs to write the previous log record to disc.
stBlk	P12M_STAT_BLK struct (read from controller via group read at tick)
stBlk.mjd	double day	40	utc mjd time stamp for the data read back.The units are days, the resolution is ms. We run the system clock in utc, not ut1 (dut1 set to 0). All of the values in stBlk are at this timestamp.
stBlk.st	P12M_STAT_WORDS (4 32bit statwords from controller (as 4 bitfields)
stBlk.st.azM	32bit	48	azimuth master 32bit status word
stBlk.st.azS	32bit	52	azimuth slave 32 bit status word
stBlk.st.el	32bit	56	elevation 32 bit status word
stBlk.st.cen	32bit	60	central processor status word
stBlk.aPos_D	dbl deg	64	azimuth position read from encoder at mjd timestamp
stBlk.azErr_D	dbl deg	72	azimuth error read from controller. It is the tracking error when locked to trajectory, or the error to follow the request path to lock (if not locked)
stBlk.azFdBackVel_DS	dbl deg/sec	80	azimuth velocity read back from controller deg/sec
stBlk.azMotCur_A	dbl amps	88	azimuth master motor current
stBlk.azSlMotCur_A	dbl amps	96	azimuth slave motor current
stBlk.elPos_D	dbl deg	104	elevation position read back from controller.
stBlk.elErr_D	dbl deg	112	elevation tracking error (see azimuth description above)
stBlk.elFdBackVel_DS	dbl deg/sec	120	elevation velocity read back from controller
stBlk.elMotCur_A	dbl amps	128	elevation motor current
tickTmIsec	long sec1970	136	time at this tick (integral). This is the time base used for where we are.
statWd	32bit	144	p12mProg statword. 32 bit  field. Contains status on what the program is doing.
numIoThrds	int cnt	148	number of i/o threads currently talking to p12mProg. These are the programs sending commands or querying status.
frListFrBufs	int cnt	152	number of free message buffers (1024) in total. the different threads communicate with messages (i/o threads to Xf thread, xfThread to loggingThread)
nDevConnectOk	int cnt	156	number of times the xfThread has successfully connected to controller. A reconnect occurs of the controller does not reply to a request.
nDevConnectFail	int cnt	160	number of time reconnects to controller failed (timed out).
trkArFreePnts	int cnt	164	number of free locations in track array (1000 max). This is no longer used (since grp reads don't use the track array).
pl	P12M_LOG_DATA_PL .. requested data: When using the track array, these were the requests computed 2 seconds in the future. When we switched to group read, these are the requests computed at the tick and then immediately sent.
pl.azReqD	dbl deg	168	requested azimuth position we send to controller
pl.elReqD	dbl deg	176	requested elevation position we send to controller
pl.corAzD	dbl deg	184	azimuth correction (little circle). This is the model plus any greatCircle offsets (from dbg gc azOff elOff) This value is added to the computed (radec->azel) position. pl.azReqD=azCmp + azCorD
pl.corElD	dbl deg	192	elevation correction. This includes the model  (with refraction included).
pl.modelCorAzD	dbl deg	200	computed model correction for azimuth (little circle)
pl.modelCorElD	dbl deg	208	computed model correctio for elevation (includes refraction)
pl.modelLocAzD	dbl deg	216	the azimuth position used to compute the model.
pl.modelLocElD	dbl deg	224	the elevation position used to compute the model (before refraction).
pl.raJReqD	dbl deg	232	requested ra J2000 position (back computed from azcmp so it includes any rates or offsets). This is where we should have been pointed
pl.decJReqD	dbl deg	240	requested dec J2000 position (back computed from elCmp)
pl.c1OffCumD	dbl deg	248	if you apply an offset and or rate (in the same coordinate system) then this will be the cumulative offset. Normally used when doing crosses in az,el. If the offset,rates are great circle then this is great circle. If the rates and offsets are in different coordinate systems then this is probably junk...This would be az
pl.c2offCumD	dbl deg	256	cumulative offset for second coordinate (see above).
pl.dut1sec	dbl sec	264	dut1 used for this time stamp (ut1-utc)
pl.tickTmIsec	long sec1970	272	the time stamp for this request packet. For Group reads it should match .tickTmIec above (it was added when we were computing things 2 secs ahead with trackarray).
azErrD	float deg	280	computed azimuth error: Requested - Actual  interpolated to the readback timestamp
elErrD	float deg	284	computed elevation error: Requested - actual (readback)
gcErrD	float deg	288	great circle pointing error (requested - actual):sqrt((azerr*cos(el))^2 + elErr^2))
fill	int	292

 

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Accessing the logfile:   (top)

    There are idl routines to access the contents of the logfile:

• idl71
• @phil
• @p12minit
• logfile='/share/phildat/p12m/logdata_20150128.dat'
• openr,lun,file,/get_lun
• nrecs=86400l
  
• n=p12mgetlog(lun,dat,nrecs=nrecs,/dcd)
• help,dat,/st
  

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