View source for Spectrometer Rotation

===NOTICES IN EFFECT===

 '''[[Pion-LT_specific_shift_instructions#Small_Angle_Rotation_instructions|Fall 2021 Pion-LT Small Angle Rotation Instructions]]

 '''HMS rotation stalls and turns off around 21 degrees. If this happens, wait 15 secs and restart the rotation.[https://logbooks.jlab.org/entry/3648669]'''

 '''If the spectrometer rotation has an error and will no reset, call the RC.'''

== SPECTROMETER ROTATION INSTRUCTIONS ==

'''Before we begin...''' Rotating the Hall-C spectrometers is pretty easy ... maybe ''too'' easy! Remember that you're moving a very large, very heavy object that can do lots of damage if it hits something, runs over something, or pulls on a cable or rope that is tied to something else. If the Hall-C technicians or engineers have certified the spectrometers as 'ready for rotation' then it is safe to proceed -- unless there is the possibility that you or somebody else left a cable, ladder, hose, etc. in the wrong place since the technicians checked. Just THINK before you act.

The limits for remote rotation are shown at the top of the Rotation screen. When desired angles fall outside the remote rotation limits, rotation must be done by an expert (Steve Lassiter) while in the Hall. 

=== Rotation GUI Screen -- Rotating a spectrometer ===

  The rotation control screen is part of the Spectrometer Magnets GUI. If you need to start it, the magnet screen is brought up on any hcdesk machine by the command '''go_magnets'''.

*Open the Rotation GUI by clicking on the '''ROTATION''' button on the top left of the magnet screen:  [[File:rotate_RootMenu.png]]

*The rotation screen will now appear. The same screen controls both the HMS and the SHMS. Do not try to move both spectrometers at the same time. 

The large box on the right will have a <span style="color:green">'''green'''</span> button indicating which spectrometer is '''Selected'''. If you want to rotate the other one, press the grey button that says '''Select''' (the other one).  In the screen image below, the '''HMS''' is Selected for rotation.

[[File:Rotation_gui_30.png]]

*On this screen, the current HMS angle is shown to be 13.5 degrees. A new angle (30 degrees) has been entered in the '''Rotate To:''' box. By typing '''30''' and pressing '''RETURN''' (or ENTER) on the keyboard, this will set the new rotation angle. 

* Next, press '''Push to Enable'''. Three buttons, '''START''', '''RESET''', and '''STOP''' will appear, as shown below. 
**To begin moving the selected spectrometer, 
**#press '''RESET''', 
**#'''Wait 10 Seconds,''' 
**#then press '''START'''. 
**You should monitor the rotation progress on both the GUI and on the TV camera that views the correct angle scale. If the spectrometer does not start moving in the first 5-6s after pressing '''START''', then you should immediately press '''STOP''' and you can try again from the beginning!!!
 NOTE: Be sure you are looking at the 'Live' angle camera image.  You should see the timestamp on the lower-right corner change every second.
  If you do not see the camera image move, stop and evaluate what is going on.  It is rare, but possible, that the image from the camera
  itself is 'stuck' ([https://logbooks.jlab.org/entry/3616512 HCLOG 3616512])
**If needed, you can halt spectrometer movement by pressing '''STOP'''. 
**'''If there is no movement within 15 seconds after pressing START, hit the STOP button or you may have to go into the hall to reset the shunt trip breaker!!'''
*If you want to back out of the procedure without moving the spectrometer, press the '''RESET''' button and then '''Select''' (other spectrometer).
[[File:Rotate_SHMSguiEnabled.png]]

=== Status Lights / Rotation Faults and Interlocks ===
====<span style="color:darkorange">''Please record all interlocks or error messages that pop up on the interlock pages as this is a great aid in debugging what has failed.''</span>====

The box on the lower-right of the rotation GUI shows the rotation system status. Generally, '''<span style="color:green">GREEN</span>''' is good. '''<span style="color:red">RED</span>''' indicates that something is wrong.

*'''Power On''', '''Remote''', and '''Auto''' should have green indicators.
*The square '''HMI Alive''' indicator to the left of the status box should be green, indicating that the control system is actually working and the process has not hung or crashed.
**If the '''HMI Alive''' indicator is red...
**#Try killing and restarting the 'go_magnets' screen.
**#If that does not work, contact ''Hall-C Engineer On Call''.

Any <span style="color:red">RED</span> status lights indicate a fault that needs to be cleared before you will be allowed to rotate. Here they are and the procedure for clearing each one:

*HMS Drive Controller
# This fault condition will prevent ''both'' HMS and SHMS from moving.
# With '''HMS''' Selected, press '''RESET''' to attempt to clear the fault.
# If it will not reset remotely, contact an expert who can enter the hall to reset the Shunt Trip Breaker.
*SHMS Drive Controller
# This fault condition will prevent ''both'' HMS and SHMS from moving.
# With '''SHMS''' Selected, press '''RESET''' to attempt to clear the fault.
# If it will not reset remotely, contact an expert who can enter the hall to reset the Shunt Trip Breaker.
*Proximity Switch Indicators mean that a spectrometer position limit switch has been activated. Normally, this should not occur. Contact the ''Hall-C Engineer On Call''.
**SHMS Forward Prox.
**SHMS Reverse Prox.
**HMS Forward Prox.
**HMS Reverse Prox.

*HMS input angle close to minimum angle.
** Watch the live video extremely closely so as not to exceed minimum angle. If it going to exceed, hit the '''Stop''' button in the GUI. If this does not work, hit the Rotation Crash button for the HMS.
*Input angle for HMS will violate minimum spectrometer separation angle. (See minimum angles on Rotation screen.)
*SHMS input angle close to minimum angle.
** Watch the live video extremely closely so as not to exceed minimum angle. If it going to exceed, hit the '''Stop''' button in the GUI. If this does not work, hit the Rotation Crash button for the SHMS.
*Input angle for SHMS will violate minimum spectrometer separation angle. (See minimum angles on Rotation screen.)

==Adjusting the angle offsets==
*The TV cameras are the primary references for the spectrometer positions (angles). The digital readouts shown in the GUI windows rely upon a passive wheel with optical encoder and a couple of calibration constants. It is possible for the wheels to slip over time. '''Do not change the offsets from where they are set for now'''
<!--*If the digital readout has drifted far from the TV readout, you can adjust it (for each spectrometer separately):
*#'''Make sure that NEITHER spectrometer is moving.'''
*#In the 'offset' box, enter the difference '''[TV_Angle - GUI_Angle]''' (rounded to nearest 0.01 degrees) and press ''ENTER'' or ''RETURN''.
*     Repeat the last step until the difference is less than 0.01 degrees.-->

==A few logbook entries from December, 2017 ==  

* [https://logbooks.jlab.org/entry/3506190 Rotation of HMS working now]
* [https://logbooks.jlab.org/entry/3507581 Summary of work to restore spectrometer rotation control]
* [https://logbooks.jlab.org/entry/3507594 Follow-up Re: Summary of work to restore spectrometer rotation control]
* [https://logbooks.jlab.org/entry/3514791 Rotation controls updated] <-- A bug in the rotation code was fixed here.