X25 Technical Documents

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Starting and Restarting the MGU User Gap Control

Launch X25 MEDM

Launch the X25 User Gap Control MEDM as pxuser on the x25-h server from the epx_setup directory as follows: x25-c_pxuser 1% ssh pxuser@x25-h.nsls.bnl.gov x25-h_pxuser 1% cd epx_setup x25-h_pxuser 2% X25

This brings up the integrated X25 beamline control MEDM as shown below. The gap control window at right displays the CRUE status and the current gap encoder reading. In this example user gap control is disabled and the gap is fully open for a ring fill.

Launch Detailed Gap MEDM

Click on the 'MGU Control' field (above) to obtain the full User Gap Control MEDM. Its values will agree with those dispalyed on channel 18 of the NSLS TV. The MEDM's first 6 parameters are readback values from the physical MGU control and the last two are user gap target requests as follows: Param Definition Values CRUE Control Room User Enable ON / OFF ERROR MGU physical controller error OK / Err In Progress Gap adjustment reporter In Process / Idle C-Sum Error Serial line check sum OK / Err Set Point Physical Gap Set Point 5.6 - 20.0 mm Avg Encoder Gap Encoder Reading 5.6 - 20.0 mm Gap Setting User GAP Setting Request 5.6 - 20.0 mm Set Gap Input of manual gap target 5.6 - 20.0 mm

Note:

The 'Gap Setting' is the target that the x25Mgu EPICS record processor transmits to the physical MGU controller. That target will be reached when CRUE is ON and the 'Gap Setting' differs by more than 0.005 mm from the current 'Set Point'. The target remains unchanged during ring fills when operators take over the MGU control (CRUE OFF) and open the gap maximally, and it will automatically be reached again when CRUE is returned to ON. A new 'Gap Setting' is obtained either from an input into the 'Set Gap' field, or more typically it is caluclated by this EPICS record processor when CBASS defines a new wavelength.

Start x25-h EPICS IOC

The User Gap Control at X25 is part of the EPICS IOC on x25-h. If this process is not up and running, the value fileds in the x25Mgu MEDM (shown above) are blank and white. The EPICS IOC running on x25-h under linux needs to be restarted by pxuser as follows: x25-c_pxuser 1% ssh pxuser@x25-h.nsls.bnl.gov x25-h_pxuser 1% start_mgu The MEDMs shown above will now repopulate after a short delay. If this is not the case, or if a segmentation fault message appears, repeat the 'start_mgu' command. The window used to 'start_mgu' may be closed using its [x] field. (supplemental info).

Updated 10 July 2006	Security Notice   Webteam   Site Map   Bio   PXRR   NSLS   BNL