Difference between revisions of "HV HowTo for Users"

Revision as of 13:47, 27 January 2014

High Voltage Instructions -- the basics

The High Voltage is controlled by LeCroy 1458 crates and associated modules like the 1461N. A trailing "N" means negative, and a "P" means positive HV.

Simplified Instructions : To control the HV in Hall A, do the following

Login as "adev" on the "adaql1" or "adaql2" computers.

cd ~adev/slowc

To run the Left HRS alone: ./hvs LEFT

To run the Right HRS alone: ./hvs RIGHT

To run the beamline crate: ./hvs BEAMLINE

Links to more HV help

I haven't gotten around to adaping this yet, but these two links provide some old but useful instructions

http://hallaweb.jlab.org/equipment/daq/HVhelp.html

http://hallaweb.jlab.org/equipment/daq/gen_slow_control.html

For experts

https://hallaweb.jlab.org/wiki/index.php/HV_HowTo_for_Experts

TroubleShooting for Users

A number of things can go wrong. If these solutions don't work for you, call an expert.

1. Changes to the HV GUI may seem slow or "take forever". First, give it 30 sec to respond to a change. There seems to be small probability (of order 5%) that the server doesn't respond, and the solution appears to be to toggle something on the HV GUI. E.g. change the HV by 1 volt or toggle the enable button off and then on. A small change like this "wakes up" the server. (I'm still trying to understand why this happens.)

2. Is the HV crate on ? There are two power supplies which must be turned on. Turning "on" in software will only turn on the HV if the hardware switches are in the right state and the electrical cables are plugged in.

3. If multiple cards seem "bad" (leading to symptom 5), I've found that power-cycling the HV crate helps ! And what I mean by power-cycling is you go to the crate and manually turn it off (cutting power), then on. NOT just via the GUI but actually the hardware.

4. The Java GUI cannnot connect to the server. Note, the server runs on a PC and talks to the HV crate via a serial connection. If the server isn't working for some reason, rebooting the PC may help. The server should then restart automatically. The name of the PC is discovered in the tab corresponding to that crate; e.g. intelha3 on Left HRS.

5. (I think this is very rare now, but I leave it here in case.) Suppose the GUI appears to connect but the pages are incomplete or partially blank or there is a Java exception. I've noticed this when the cards give incomplete data strings and the Java GUI cannot handle it. This is related to the problem mentioned in #1. See also 6.

6. Another reason for #5 is that a card may be bad or seems bad. The solution is to run some low-level diagnostics, find the card that does not talk, and replace it (but note that power-cycling might help, see point 3). You may need to call an expert for this step.

7. Need the sign ! Most of our cards are negative HV, and when you enter the target HV, you must also enter a minus sign. Like "-852" and not just "852". Beware !