menzel
3d24ea5651
at_each_point issues the line move and then sleeps before firing the
burst. The sleep was acc_time alone, which covers the acceleration ramp
and nothing else -- while the move still has to cross the scan server ->
device server -> EPICS -> controller path first. acc_time shrinks with
the scan velocity; that path does not. On a slow scan the burst
therefore began well before the stage moved, and the first points of
every line piled up at the line start.
Measured from the position readback of five commissioning scans, as the
distance the stage was behind the trigger grid once the lag stopped
growing:
scan exp_time v_cmd lag latency
254 20 ms 0.5 mm/s 29.7 pts 0.594 s
450 50 ms 0.1 mm/s 11.9 pts 0.595 s
324 15 ms 0.667 mm/s 41.5 pts 0.623 s
473 100 ms 0.065 mm/s 6.3 pts 0.630 s
411 50 ms 0.1 mm/s 12.7 pts 0.635 s
Constant to +-3.5% across a 6.7x range of exposure and a 10x range of
velocity, on two axes. Scan 473 is sampled 74 times per line and shows
the shape plainly: the lag appears in the first interval and then holds
at 6.3-6.4 points for the rest of the line while the velocity sits at
exactly the commanded 0.065 mm/s. A start-up offset, not a velocity
error, and the stage itself is blameless.
Deliberately not solved by polling for motion. Observing the readback
costs a round trip of this same ~0.6 s, so it would trade a systematic
offset for a jitter of similar size -- and a constant offset displaces
every line equally, where a varying one shears the image line by line
and cannot be undone afterwards. The reproducibility is the asset here,
not the enemy.
The value lives on ddg1 next to the shutter delay, with a setter in
USER_ACCESS, because that is where cont_grid already fetches its trigger
timing. It is not a property of the delay generator and the docstring
says so. Setting it to 0 reproduces exactly the previous timing without
a redeploy, which is the intended way back if this makes things worse.
The real fix is to trigger the DDG from the motor
(scan_type: hardware_triggered), taking the round trip out of the timing
chain rather than compensating for it. This is the stopgap until then,
and it rests on the latency staying constant -- which is worth
re-checking with the same measurement whenever the deployment changes.
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)