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Controls

The control stack and trigger scheme. Design-phase; handles not yet recorded.

7-BM runs on the APS EPICS control stack, the same stack 2-BM uses. Unlike TomoWISE (which runs MAX IV Tango/Sardana), there is no control-system difference from the APS pilot here.

Device handles

CORA models each device's control handle as an opaque string set at the edge. For 7-BM the EPICS PV names are not yet recorded in this scaffold, so every device's handle is left empty in the descriptor rather than filled with an invented value. Wiring each Asset to a real PV is tracked by CTRL-1 on Open questions.

Timing and triggering

Timing is a heavier subsystem at 7-BM than at 2-BM, because the time-resolved techniques (high-speed imaging, radiography) need hardware-gated triggering synchronized to the storage ring. The scheme:

  • Two Stanford DG645 delay generators. One is synced to the storage-ring P0 signal (271 kHz); the other delays the chopper-to-camera trigger so the camera fires when a chopper opening reaches the beam.
  • A softGlue FPGA for low-level logic (counters, gates, signal decimation).
  • The Machine Status Link P0 reference, synchronized to the electron beam.
  • A top-up inhibit signal that goes high before a ring top-up and vetoes acquisition during the unstable window, so time-resolved data is not taken during top-up.

The whole scheme is modelled as a single TimingController device carrying it, mirroring the 2-BM Timing device (the softGlueZynq box). Whether any of these elements deserves separate modelling is TIMING-1.

The floor: several orchestrators, not one

A 7-BM-specific seam observation, recorded for the eventual Conductor work: where 2-BM has one acquisition orchestrator (tomoScan), 7-BM's floor carries several technique-specific ones, listed in the descriptor's software_iocs_not_modeled:

  • tomoScan for tomography (shared with 2-BM).
  • DataGrabber (Java) for time-resolved radiography, handshaking over the EPICS busy record 7bmb1:rad:get_data.
  • The ADQ14 Python scripts bridging the EPICS scan record to the digitizer soft IOC.
  • The EPICS scan record for step scans.
  • The high-speed-imaging string sequence for chopper-gated movie bursts.

These are control-system software, not CORA Assets. They are recorded here because they are what a future CORA Conductor would orchestrate over or replace: 7-BM tests whether "replace the technique orchestrator" generalizes across several distinct floor engines, where 2-BM had only one.

See Open questions for the control and timing items still to confirm.