Online FILLM

Data Archive System

Observing Guides & Tools

Online Filling with FILLM


1 - Introduction

Online filling of VLA data is available at the AOC. Online (or realtime) FILLM is very similar to the more familiar offline FILLM. The main difference is that offline FILLM reads from a tape drive, whereas online FILLM receives data from disk. Depending on the workstation, one or more tape drive numbers are reserved for online use; at AIPS startup a list of all available tape drives - including the online pseudodrives are listed. Set INTAPE to a number listed as being reserved for online data filling, and type MOUNT. If there is no realtime FILLM tape device listed at startup, ask one of the AIPS support people to help you. Before starting FILLM, make sure you run the correct version by typing:  version 'online'.

2 - Interactive control

The user can determine interactively whether new data should be appended to existing files, or be put in newly created files. This is regulated by the first element of the hidden adverb APARM. Hidden means that APARM can only be specified using the TELL mechanism during the execution of the task: it will not show up in INPUTS FILLM, but it will in SHOW FILLM. Both on and offline FILLM start with the option to append data to newly created files (or older files, if DOCONCAT=1), whenever possible. This behavior can now be changed interactively using TELL FILLM according to the following table:
APARM(1) OPTELL procedure meaning
  QUIT quit finishes current scan, then quits
0 CHAN few appends scans to existing data whenever possible
1 CHAN many creates a new file for each scan
2 CHAN break closes files after current scan, then continues in few mode
3 CHAN stop like quit, but does not wait for current scan to end

In the previous table, the listings under procedure are short. AIPS procedures which execute the TELL command and give it the proper OPTELL and APARM(1). Perhaps the most useful option is break. This closes the file when the current scan is finished, creates a new file, but after this appends further new data to this new file. The closed file is ready to be viewed and analyzed by AIPS software. This might well become the standard way of running online FILLM: let FILLM append until the user tells FILLM to close the file and create a new one. This new file will receive all the new data until the users tell FILLM again to break.

3 - Ending FILLM

There are three ways to end FILLM. abort is instantaneous, and will probably leave the output files in a corrupted state. The other two possibilities properly close the FILLM output: stop takes as long as the TELL command takes to be recognized, at the most 1 - 2 minutes. quit allows FILLM to finish the current scan first, which may take much longer. Finally, FILLM will end automatically under certain conditions, described in the following section.

4 - VLAOBS and subarrays

FILLM may be started ahead of time, before the proposal code of interest has begun. FILLM's starting and finishing is governed by the adverbs VLAOBS - specifying the program code for the observation to be filled - and CPARM(6) (subarray number) as listed in the following table:

VLAOBS CPARM(6) action
non-blank   0 FILLM starts when VLAOBS begins in any subarray.
That subarray becomes the current subarray
FILLM ends when a different program code in that subarray starts
non-blank >0 FILLM starts when VLAOBS begins in the specified subarray
FILLM ends when a different program code in that subarray starts
blank   0 FILLM loads data from all program codes in subarray 1
FILLM has to be stopped interactively.
blank >0 FILLM loads data from all program codes in the specified subarray
FILLM has to be stopped interactively.

The first case, VLAOBS non-blank, CPARM(6) = 0, is the recommended mode of running online FILLM: the user does not have to know about the actual subarray, and FILLM exits automatically. There is one caveat: under some circumstances, after program code VLAOBS has executed, there may not be another program starting in the same subarray for a long time. In that case FILLM does not finish automatically, and the user will have to stop FILLM by hand. Make sure to enter the correct program code: if you specified proposal code AV65 in the observe file, FILLM will look in vain for e.g. VLAOBS='AV065'.

5 - Example

>INTAPE2 listed as realtime drive at AIPS startup
AIPS 1: Mounted on-line tape device on local host
>version 'ONLINE'
>vlaobs ' ' fill current observing program
>go fillm
AIPS 1: Found in Version=ONLINE
FILLM: Task FILLM (release of 15JUL95) begins
FILLM: UV data will be written in compressed format
FILLM: Welcome to real-time FILLM!
FILLM: Shadow flag limit = 2.500E+01 meters.
AIPS 1: Resumes
FILLM: MCINI: Processing Correlator Code ' ' with 27 antennas.
FILLM: MCINI: Processing Correlator Code ' ' with 27 antennas.
FILLM: Program = AK383 ; Tape revision number = 24.
FILLM: Create 14/02/95 .L BAND. 1 (UV) on disk 2 cno 1
FILLM: Ref. date = 14/02/095 A-C = 1.464900 B-D = 1.385100 GHz
FILLM: FLMFQ: FQ entry tolerance = 1.000D+02 1.000D+02
FILLM: Found 1857+039 : 1 50.000 MHz at IAT 0/ 16 45 0.
>stop issues TELL command for graceful exit
AIPS 1: Found in Version=ONLINE AIPS'> reaction to TELL command
FILLM: has been told to change parameters FILLM's reaction to TELL command
FILLM: Read 1404 visibilities from 1 file
FILLM: Appears to have ended successfully

6 - Common problems and their causes

Problem: On starting FILLM, you receive the following message:


Solution: you have not mounted a tape drive. Find out a correct tape number and do a MOUNT.

Problem: On starting FILLM, you receive the following message:

FILLM1: this usually means PARITY ERROR

Solution: You are running regular FILLM. Set the AIPS version to ONLINE and restart FILLM

Problem: While running FILLM, commands like stop and break are not recognized.

Solution: Do a RESTORE 0 and try again.

Content reviewed on: 16-October-2006
Reviewed by: Meri Stanley

Page maintained by Jeff Goldin