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Overview

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CXI has two in-vacuum 2.3M CSPAD pixel-array detectors.  Each detector is stationed downstream of one of CXI's three interaction points and can be read-out individually, together, or independently – allowing CXI the capability to operate two experiments simultaneously using a single X-Ray beam.  When running two experiments during the same shift, the upstream experiment uses the DS1 CSPAD in the primary DAQ from cxi-daq, while the downstream parasitic experiment will use the DS2 CSPAD in the secondary DAQ from cxi-monitor.

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DS1 and DS2 have companion mobile equipment racks, named D50 and D51 respectively.  The racks are nearly identical twins and each contain power supplies and readout electronics for detectors, a Digi, a 4-channel stepper motor controller and an EPICS IOC server.  The mobile racks handle controls and feedback for detector power and diagnostics, some stepper motor control, and serve as an interface for detector data and timing input/output.  A rack profile listing of the mobile racks' devices is shown below.  

Mobile Rack Vertical Layout

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1	CSPAD Concentrator	Handles CSPAD data readout
2	Detector PDU	Consolidates power from MPOD with other analog control and timing signals to detector input
3	MPOD	EPICS controllable High/Low voltage power supply for detectors
4	EPICS IOC Server	IOC for motors, encoders and power supplies running from the mobile rack
5	Digi Serial Port Server	Serial communication input/output terminal
6	Dumb Motor Controller	For in-vacuum LS-180 CSPAD Z-stage
7	120V AC Power Supply	Power supply for mobile rack electronics
8	Motor Power Supply	Power supply for dumb motors

Mobile Rack Hosts

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Mobile Rack	IOC Server Hostname	Digi Hostname
D50	ioc-cxi-protura1	digi-cxi-21
D51	ioc-cxi-protura2	digi-cxi-31

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When a detector chamber changes locations, such as when DS2 moves from DSD to DSA, the mobile racks are powered down, IOCs disabled, and the detector chamber's external electronics are unplugged.  When the chamber is mounted at its new location, the cables need to be reconnected and its mobile rack will need to be set up again and the IOCs restarted.  The CXI Home Screen will also need to be edited to draw the control buttons under the correct detector stand location. 

Shutting Down a Mobile Rack:

PCDS OR BEAMLINE EXPERT ONLY.  Don't even try it unless you have permission from the CXI controls POC or area manager. 

1. Before turning anything off, disable the IOCs running on the server in the mobile rack.  
   1. Open iocmanager and sort by the "Host" column to list the IOC processes running on the rack's server.  
   2. Move your attention to the "State" column, and for each IOC select "Off" in its respective cell.  
   3. Navigate to the "Configuration" dropdown on the top left and click "Apply".  This will only work if your UNIX account has CXI iocmanager privileges.  You will be prompted to enter your username and password!  A pop-up window appear somewhere inconvenient and ask you to confirm your actions.  
   4. Confirm your actions..
      
      
2. Powering down the rack should be carried out in the following steps:
   1. Make sure the detectors are powered down via EPICS.
   2. Go to the rack and power down each module chassis using its front or real panel power button/switch if it has one. 
   3. Switch off the surge protectors on the rear side of the rack.  
   4. Unplug the surge protectors from the stand power outlets.
      
      
3. Carefully disconnect the grounding cable and CSPAD trunk cable TOP and BOTTOM connectors from the detector chamber flange using a hex wrench.  The pins of these connectors are fragile.  Disconnect motor and vacuum gauge cables from points J1→J7 on the I/O panel mounted to the detector stand.  Keep the cables connected to their interfaces on the rack itself as they will be needed again.  
   
4. Look down. There are a few ethernet cables running from the rack to a patch panel beneath the detector stand.  These are for connecting the rack's electronics to the CXI controls network.  Disconnect them from the patch panel.
5. There are a number of BNC cables and multimode fibers running from the CSPAD concentrator and detector PDU to nearby patch panels.  These are for detector timing and data and go to servers elsewhere in the hutch.  Disconnect them from the patch panel.
6. Disconnect the copper grounding cable attached to the bottom of the rack.

Setting Up a Mobile Rack:

PCDS OR BEAMLINE EXPERT ONLY.  Seriously make sure you have permission from the CXI controls POC or area manager. 

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Detector and Chamber Troubleshooting:

First refer to the CSPAD and PGP troubleshooting guide and DAQ troubleshooting guide for detector related problems.  These should sort things out or help narrow down the problem.  

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