Recovering from a crash

Rather than allaying your fears, it is my duty (JBH) to inform you that there are things that can go wrong in the complex Taurus - sequencer - CCD controller triangle. With good fortune, you will not see any of these problems but, unfortunately, without significant investment, we are stuck with prospect of invading hordes lurking over the horizon. Since early 2000, the system has been behaving rather well but don't let that fool you. If you follow the instructions below, most times you will be back on the air within 5 minutes.

There are several common user sequences that can lead to the system hanging. For example, one should not initiate a run_step sequence within shuffle mode, or a run_step sequence without the exposure time set. Many of these `sillies' will be trapped in the new system.
 

Terminal Servers  &  No Breaks

If nothing seems to make sense, i.e. the system works intermittently, see if any of the terminal servers have gone down. This one has caught us out on rare occasions. So what are terminal servers?

Traditionally, terminals were plugged into an RS232 interface connected directly to your computer.  This had a few implications - your terminal could only talk to one computer, your terminal couldn't be more then the maximum length of an RS232 line away from your computer, you had to run lots of RS232 lines and the number of terminals you could have was limited by the number of interfaces your computer supported.

Terminal servers fixed all that.  They are a box which sits on the network and have normally 8 or 16 RS232 ports.  The box and the computer concerned have software which makes the RS232 ports look like they are connected directly to the computer, but the software allows that connection to be made to any computer. (for Unix boxes, the software is "telnet"; for VAX/VMS, it is a protocol called "LAT"). Terminal servers make it far easier for RS232 connections in the control room and out in the Cass cage.   Instead of having to run heaps of RS232 lines from the VAX computer room, we just run a ethernet connection and have local terminal servers.  There is one in the Cass cage and two in the control room.

Most AAT instruments are controlled using RS232 connections plugged into terminal servers, which includes the  Taurus Micro and the Instrument Sequencer Micro.  The major benefit  is that, as well as having remote control, you can always fall back to plugging a VT100 compatible terminal directly into the instrument.  And it requries no special software in the (memory limited) instrument micro. The problem is that you have one more thing to go wrong, and it is something which is a bit of a mystery as it is normally hidden from you by the software.

So watch out for erratic or intermittent behaviour, i.e. shuffles and exposures sometimes work and sometimes do not. You will need one of the technical staff to reboot and fix the offending server.

An obscure problem that leads to related behaviour is one or more elements of the Taurus-2 chain that has NOT been plugged into the NO BREAK power supply. Even small power surges appear to cause problems.
 

CCD System Failure.

This happens from time to time for any number of reasons. DO NOT KILL Taurus.

Simply exit the CCD window with "exit".

Now kill the Taurus windows; this does not stop Taurus. You keep hitting "PF1" or "PF4" until you are asked whether you want to leave the SMS environment, to which you reply "yes". You are now at the VMS prompt.

At the VMS window,  type:

DCL> stop INSTSEQ
DCL> sms                        --this brings up CCD window and the Taurus windows

Now go through the Taurus setup menu as normal but do NOT reset the micro.
 

Aborting a shuffle. Before reading on, please type METHOD DEFAULT in the CCD window if you have not done so already and assuming you have the prompt. Also find SHUFFLE_TIDY under RUN_CCD in the SMS window and hit PF1.

I would advise AGAINST aborting a shuffle run.... ever. If you really, really must, this might work, at least it did for T J Farrell. I saw him do it.

Type "abort" at the CCD window.

Hit "." on the Taurus SMS window key pad. Now type:

obeyw taurus cmd "SR 0"

At the VMS window,  type:

DCL> stop INSTSEQ
DCL> sms                        --this brings up CCD window and the Taurus windows

Now go through the Taurus setup menu as normal but do NOT reset the micro.
 
 

TTF Z-value refuses to step. Before reading on, please type METHOD DEFAULT in the CCD window if you have not done so already and assuming you have the prompt. Also find SHUFFLE_TIDY under RUN_CCD in the SMS window and hit PF1.

This means that the instrument sequencer is confused.

Kill the Taurus windows; this does not stop Taurus. You keep hitting "PF1" or "PF4" until you are asked whether you want to leave the SMS environment, to which you reply "yes". You are now at the VMS prompt.

At the VMS window,  type:

DCL> stop INSTSEQ
DCL> sms                        --this brings up CCD window and the Taurus windows

Now go through the Taurus setup menu as normal but do NOT reset the micro.
 
 

Shutter stays open.

This seems to reset if you do a short run_step sequence, or a short shuffle sequence.
 
 
 

When all else fails...  How to Reset Taurus

There is a problem recovering from an aborted taurus shuffle run on TTF.
 

Assumptions

1. You have started an undesired run.
2. You do not want to loose a lot of telescope time and or require length recalibration.

Shuffle Run

1. Select CCD window
2. Type abort and answer yes to the question
3. You are now stuck in limbo
4. Select Taurus SMS window
5. Press . (Del) on the numeric keypad
6. You will now have a command prompt in the SMS window
7. enter the following command exactly obeyw Taurus STOP SLOW_RUN
8. This will terminate the IPCS slow run, but you are still in limbo
9. You must now leave your chair and press the reset button on the well labelled Taurus INSTRUMENT SEQUENCER MICRO which is located in the lowest position in the rack between the camac and network rack in the AAT control room.
10. Return to your xterm and exit the Taurus SMS window with repeated PF1 keypresses till you see the prompt DO you mean to exit from SMS? (y/n) answer yes. YOu will now have the 40A prompt.
11. Enter rvtaurus ccdn where n=1or2 as appropriate

• Hit Return on keyboard
• select detector CCD_SHUFFLE
• select reset_micro NO
• Press PF1
• You will now be able to contine to observer by entering

Run control menu
CCD control
Shuffle multi

Assumptions

Actions

1. Etalon Stepping Run
2. Enter ABORT in CCD window, answer yes and idle prompt returns
3. Correct original reason for aborting eg change increment size
4. Enter PF1 to resume interrupted run

If you have problems with the instrument please contact Technical Support, technical staff on duty at the telescope should be called if you cannot resolve the problem quickly.

Comments and suggestions to cmc@aaocbn.aao.gov.au and ejp@aaocbn.aao.gov.au