Each sample chamber at CXI has two cameras – inline and off-axis – used for alignment and automation, experiment viewing, and analysis. The image streams are served via an EPICS IOC viewable from the camViewer, and can be included in the CXI primary or secondary DAQ data streams via the IOC recorder.
Each camera has a host server that is running an EPICS IOC to handle low-level command, image acquisition, and to broadcast the data via channel access. Recorded cameras need to run on IOC hosts with hard disk drives, so the CXI sample chamber cameras run on ioc-cxi-rec03(Rack 59 : Red Hat 5) and ioc-cxi-rec04 (Rack 52A : Red Hat 7). Access to the host and IOC process can be achieved using the IOC manager. The cameras are also synced to LCLS timing, and thus require a TTL trigger signal from their host's EVR hardware – typically a SLAC EVR PCI card in the server chassis. This is usually routed from the host to the camera via a user patch panel over coaxial cable.
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Adimec Opal cameras will always sync to an external trigger, and actually work best in 'Free Run' mode. |
The Yag Viewer button will open the camViewer, from which you can select and view the camera feeds. Example: CxiSc3Inline.
As a result of changing setups, hutch reconfiguration and different experiment requirements, the cameras at the sample chambers may come and go or even change types. Most often GigE type cameras such as the Allied Vision Manta 146C or "framegrabber" type cameras such as an Adimec Opal are used. GigE cameras are dirt simple, okay? GigEs are usually powered over ethernet so they need only be connected to a trigger signal and a network switch on the cds-cxi.pcdsn subnet with PoE capability to maintain function at the sample chamber. Frame grabber cameras, on the other hand, communicate over optical fiber which is transceived on both sides by EDT RCX camera links. RCX camera links require separate power (5V), and must be configured to the correct blink code in order to send and receive data between the camera and frame grabber PCI card. If a camera link fails then the IOC host will lose connection to the camera. Frame grabber cameras are usually powered using DC voltage supply available at the user patch panels. Network and fiber connections to the sample chamber cameras are also accessed via the user patch panels.
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