S800 Troubleshooting

The gas handling system triggers a voice alarm

The HV GUI triggers a voice alarm

Check the read-back value of the voltage displayed above the "HV set" button for the detector that triggered the alarm. In the example shown below, the read-back equals the set voltage of 1000 V for the anodes of both CRDCs. If read and set voltages match and the scalers/spectra for this detector still increment, the alarm was false and shouldn't come back once acknowledged in the alarm monitor.

A tracking PPAC might occasionally trip and will trigger a real alarm. Turn it back on via the "Turn Off/Turn On" button. If it continues tripping, the rate might be to high. The two solutions are to lower the rate until the PPAC stays operational or to lower the PPAC voltage by 5 or 10 V. Please keep in mind that lowering the voltage increases the performance of the detector. If the PPACs cannot be turned on again at reduced rate or lower voltage or if the CRDCs or the ion chamber trigger a real alarm, contact somebody from the S800 group.

The NMR GUI beeps

Please follow these steps

The NMR GUI "freezes"

The NMR program is connected to the following devices and systems:

• The NMR module through a terminal server

• The digital oscilloscope through a terminal server

• The EPICS system through the caRepeater process launched by the et_wish shell running the program

Any of these connections can eventually be broken, and the program tries to catch the failures and report them to the user. However there are cases when the program “hangs” and need to be manually aborted. The little heart displayed at the top left corner of the oscilloscope display indicates the liveliness of the EPICS loop, as well as the liveliness of the program itself. If the heart stops beating for more than 10 seconds, it probably means the program is frozen. To restart it, simply click on the program's icon again, which will kill the existing process and start a new one. It has been observed that it occasionally takes two to tree tries to restart the NMR application.

In case nothing happens after trying multiple times, the connection to the NMR module is probably locked and needs to be freed. To free it, type the following from any shell window (actual typing show in this font ):

telnet 35.8.35.139
enter any username
su
System
unattach port x (where x=1 for the analysis line and x=2 for the spectrograph) repeat until nothing is connected to this port anymore
logout

Click again on the starting icon and the program will start.

Resetting the S800 alarm monitor in case of "too many alarms"

on uxpc2 start "et_wish" and enter

pv linkw a S800ALARM (links a to the S800 alarms)
set a (returns the number of alarms)
set a 0
pv putw a (resets the alarms to 0)
pv linkw m S800MESSAGE (links m to the S800 alarm messages)
set m (returns the last alarm message)
set m " "
pv putw m (resets the alarm message)
exit

DAQ crashes that require the S800 VME crate to be rebooted

Crashes of the data aquisition related to problems with the bus of the S800 VME crate have been observed and require a reboot of the crate (power cycling). Those crashes happen for the CRDC as well as for the tracking PPAC readout. A typical error message is "Failed to grab busses in crdc2_pads (slot 8)". The power supplies of the gas-filled focal plane detectors are located in this crate and require special attention. The VME crate is the topmost crate in the S800 electronics tower (toplevel of S3, on the left).

try to turn off the CRDCs and the ion chamber (anode + drift each) with the HV Gui running on uxpc2 if the GUI still responds
tell the operator that you have to enter the S3 vault, make sure it is secured
if the HV could not be turned of remotely with the GUI, flip the red HV on/off switch on the iSeg power supplies to "off" (red switch below the turn knob).
reset the VME with the appropriate switch on the control panel of the crate
after the crate is up again, switch the iSeg HV back on
secure the top level of the vault
Set the voltages of the CRDCs and the ion chamber to the previous values using the HV GUI on uxpc2

UXPC2 has to be rebooted

Start the following applications using the icons (preferably on the desktop indicated in paranthesis):

Alarm Server (S800)
Alarm Monitor (sent to all desktops)
GHS Monitor (S800)
HV (sent to all desktops)
S800S_NMR (S800)
S800A_NMR (S800)
DAQ Controls (Readout)
Scaler (sent to all desktops)
SpecTcl (SpecTcl)

Enable the alarms and log option on the HV Gui (buttons at the bottom).

Barney is only in exceptional cases supposed to be used by the experimenters.

05/09/05 11:05