menzel 778b508023
CI for csaxs_bec / test (push) Successful in 1m53s
fix(ddg1): give the shutter the time it actually needs to open
The first point of every line is under-exposed. Four commissioning scans
put a number on it, against the 2e-3 head start that was in place:

    scan   exp_time   first/near   lost
     324     15 ms       0.655     5.18 ms
     254     20 ms       0.732     5.36 ms
     411     50 ms       0.881     5.93 ms
     450     50 ms       0.879     6.04 ms

A fixed time, not a fixed fraction: it varies by 17% across a 3.3x range
of exposure while the fraction varies by 2.9x. The same deficit appears
on the integrated scattering, a different detector behind a different
gate, so the cause is upstream of both readout chains rather than in
either of them. 2e-3 allowed and ~5.6e-3 still lost means the shutter
needs about 7.6 ms.

The trigger scheme was already right -- the shutter fires on cd at t0
and the acquisition on ab is held back by _shutter_to_open_delay, with
the widths, burst_period and cont_grid's acc_time and premove all
derived from it. Only the value was wrong, and it was a literal in two
places, so setting one and not the other would have been silently undone
by keep_shutter_open_during_scan.

Lifts it to DEFAULT_SHUTTER_TO_OPEN_DELAY next to the other defaults,
with the measurement recorded, and adds set_shutter_to_open_delay to
USER_ACCESS so the value can be converged from the client instead of by
redeploying the device server. It is bounded, because a delay is paid on
every line and a fat-fingered value would stretch the scan rather than
fail.

Cost at the new value is 5.6 ms per line -- 0.25 s over scan 450 -- and
0.8 um of extra premove.

The existing stage test asserted the 2e-3 literal and now asserts the
constant. New tests cover the default, the bound, the USER_ACCESS entry,
that a set value actually reaches the ab channel while cd still fires at
t0, and that keep_shutter_open_during_scan discards a tuned value, which
is a sharp edge worth pinning rather than leaving to be rediscovered.
2026-08-25 21:03:21 +02:00
2026-08-19 12:03:18 +02:00
2025-05-24 11:37:51 +02:00

cSAXS BEC

cSAXS specific plugins and configs for BEC This document guides you through the procedure to spin up BEC at the beamline for a new experiment (e-account). You might want to run cSAXS copy scripts before in case you want to have the former data structure to be preserved.

Overview

  • Clone cSAXS BEC repository into e-account (e.g. into ~/Data10/software/.)
  • Start Epics iocs
  • Start BEC, BEC server and load/modify the device config with relevant hardware
  • BEC commands

Clone cSAXS BEC repository

Clone the current cSAXS BEC repository from GIT into the new e-account. Create directory

mkdir ~/Data10/software
cd ~/Data10/software

Clone repository

git clone https://gitlab.psi.ch/bec/csaxs_bec.git

Start epics iocs

You can start up the iocs while the ./setup_bec.sh script is running. Be aware though that the scripts requires you to interact with it.

DelayGenerator

Open a new tab in a terminal in comp1/comp2 or cons1 and follow the commands below:

ssh gac-x12sa@localhost
cd ~/delaygen
iocsh -7.0.6 startup.script

Be aware -7.0.6 is referring to the current epics version and might change in future (SLS 2.0). To start the epics panel (only if needed), run in a new shell

caqtdm -noMsg -macro P=delaygen:,R=DG1: srsDG645.ui

More notes on usages and cabelling of DDGs. Currently 3 generators are used:

  • DDG1 for detectors (EXT Enable from SGalil stages, T0 to DDG2, AB for eiger, CD for Falcon, EF for Pilatus_2)
  • DDG2 for mcs card (ext. enable from DDG1, AB to mcs card)
  • DDG3 for fast shutter and mcs enable (AB short pulse to enable MCS (needed!!), CD to keep FSH open )

Eiger

Open a new tab in a terminal in comp1/comp2 or cons1 and follow the commands below:

ssh gac-x12sa@localhost
cd ~/Software/Eiger/
./launch_ioc

A live view of status and images for std_daq can be found here xbl-daq-29:5000.

Pilatus_2

First, start the cam server. Connect to the computer and follow the instructions printed after connecting:

ssh det@x12sa-pd-2 (Pilatus2)

The cam server will open, wait until you see **. Nex step, open a new tab in a terminal in comp1/comp2 or cons1 and follow the commands below:

ssh gac-x12sa@localhost
cd ~/Software/Pilatus300K/
./launch_epics

FalconX1

Open a new tab in a terminal in comp1/comp2 or cons1 (logged in as the current e-account) and follow the commands:

ssh x12sa-cons-01
cd /ioc/X12SA-PC-FALCONX1/
iocsh -7.0.6 startup.script

Be aware -7.0.6 is referring to the current epics version and might change in future (SLS 2.0)

Start BEC, BEC server and load device config

Step 1 needs to have finished for continuing with these steps. What remains now is to start the bec server. Connect to pc15543 and open a new terminal to run:

cd ~/Data10/software
source bec_venv/bin/activate
bec-server start
tmux attach -t bec

Open another teminal on pc15543 and start BEC:

cd ~/Data10/software
source bec_venv/bin/activate
bec

Note: In case there is a warning after starting BEC that it was not able to import scilog, you will have to pip install scilog in the bec_venv to be able to send printouts to scilog from the command line. Within a new terminal:

cd ~/Data10/software
source bec_venv/bin/activate
pip install scilog

Device config from csaxs-bec plugins

bec.config.update_session_with_file('/sls/X12SA/data/e20639/Data10/software/csaxs-bec/bec_plugins/configs/bec_device_config_sastt.yaml')
bec.config.save_current_session('~/Data10/software/current_config.yaml')

The second command is helpful if you adjust limits of motors, which will then be stored in the config and loaded if a reload of the configuration is needed.

BEC commands

A number of commands that are useful:

To move devices that are added in the config:

umv(dev.samx, 0) #absolute
umvr(dev.samx, 0) #relative
dev.samx.wm #print motor position and limits
dev.samx.limits = [low_limit, high_limit] # To set limits, note, same lower and higher limit, e.g. [0, 0] means no limits!!

Scans:

scans.acquire(exp_time = 0.5, frames_per_trigger=10, readout_time=3e-3) # equivalent to a loopscan 30 0.5
scans.line_scan(dev.samx, -1, 1, steps=20, exp_time=0.5, readout_time=3e-3, relative=True) # optional, add frames_per_trigger =10 for burst acquisition at each step
#Scan 2 motors in a step scan at the same time
scans.line_scan(dev.samx, -1, 1, dev.samy, -1, 1, steps=20, exp_time=0.5, readout_time =3e-3, relative=True) # step scan with 20 steps, again frames_per_trigger can be added for burst at each point
scans.sgalil_grid(start_y = , end_y = , interval_y = , start_x=, end_x=, interval_x =, exp_time=0.5, readout_time=3e-3, relative=True)
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