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Table of Contents
Introduction

LCLS2 DAQ supports three types of scans:

epics PV step-scans using bluesky.
"on-the-fly" scans of epics PVs
detector configuration scans

On-The-Fly Scans

These are the simplest scans to run where the DAQ is free-running and a PV is changed while taking data. It's advantages are that it is simpler to run and sometimes quicker (since one does not pause the DAQ to move a motor, for example). A disadvantage is that on a per-shot basis one does not know the precise value of the PV, since the PV is typically only recorded at 1Hz in epicsArch. An example script to move a PV while the DAQ is taking data:

Code Block

language	py

from epics import caget, caput, cainfo
val = 790000
delta = 7000
import time
while 1:
    val += delta
    caput('IM3K4:PPM:CAM:EVR:TRIG4:TDES',val)
    print(caget('IM3K4:PPM:CAM:EVR:TRIG4:TDES'))
    time.sleep(5)

EPICS PV Step-Scans

EPICS PV step scans use the BlueSky software from BNL (https://nsls-ii.github.io/bluesky/). In this mode one or more PV's are modified while the DAQ is paused, then data is acquired (either for a fixed number of shots or a fixed time) then the DAQ is paused again and the PV is modified again for the next "step". BlueSky supports complex coordinated motion of multiple PV's.

An example python script has been created to demonstrate support for PV scans with the RIX instrument.

The source code is here: https://github.com/slac-lcls/lcls2/blob/master/psdaq/psdaq/control/rix_bluesky_scan.py

This script scans a simulated motor at 15 equally spaced points from -10 to 10, recording 120 events at each point. The number of events per step can be adjusted using a command line argument. A user with knowledge of the direct motor should update the script to replace the simulated motor.

The parameters of the scan should be updated to match the requirements of the experiment. To do so, update this section of bluesky_rix.py:

Code Block

language	text
title	bluesky_rix.py scan parameters

# Scan motor1 from -10 to 10, stopping
# at 15 equally-spaced points along the way and reading dets.
RE(scan(dets, motor1, -10, 10, 15))

Here is the script running with default settings (see below for optional arguments):

Code Block

language	text
title	rix+bluesky_scan.py demo

$ python rix_bluesky_scan.py 

Transient Scan ID: 1     Time: 2020-12-10 18:24:53
Persistent Unique Scan ID: '2092a9ca-160c-4b52-8683-256f699e1e01'
New stream: 'primary'
+-----------+------------+------------+
|   seq_num |       time |     motor1 |
+-----------+------------+------------+
|         1 | 18:24:58.5 |    -10.000 |
|         2 | 18:24:59.6 |     -8.571 |
|         3 | 18:25:00.6 |     -7.143 |
|         4 | 18:25:01.6 |     -5.714 |
|         5 | 18:25:02.7 |     -4.286 |
|         6 | 18:25:03.7 |     -2.857 |
|         7 | 18:25:04.8 |     -1.429 |
|         8 | 18:25:05.8 |      0.000 |
|         9 | 18:25:06.8 |      1.429 |
|        10 | 18:25:07.9 |      2.857 |
|        11 | 18:25:08.9 |      4.286 |
|        12 | 18:25:10.0 |      5.714 |
|        13 | 18:25:11.0 |      7.143 |
|        14 | 18:25:12.0 |      8.571 |
|        15 | 18:25:13.1 |     10.000 |
+-----------+------------+------------+
generator scan ['2092a9ca'] (scan num: 1)

Code Block

language	text
title	lab3_bluesky_scan.py demo

$ python lab3_bluesky_scan.py 

Transient Scan ID: 1     Time: 2021-02-21 16:33:15
Persistent Unique Scan ID: 'fb4d16b7-2844-431e-bb77-cc90cd1f2fe0'
New stream: 'primary'
+-----------+------------+------------+
|   seq_num |       time |     motor1 |
+-----------+------------+------------+
|         1 | 16:33:19.7 |    -10.000 |
|         2 | 16:33:19.8 |     -8.571 |
|         3 | 16:33:19.9 |     -7.143 |
|         4 | 16:33:20.0 |     -5.714 |
|         5 | 16:33:20.1 |     -4.286 |
|         6 | 16:33:20.3 |     -2.857 |
|         7 | 16:33:20.4 |     -1.429 |
|         8 | 16:33:20.5 |      0.000 |
|         9 | 16:33:20.6 |      1.429 |
|        10 | 16:33:20.7 |      2.857 |
|        11 | 16:33:20.8 |      4.286 |
|        12 | 16:33:20.9 |      5.714 |
|        13 | 16:33:21.0 |      7.143 |
|        14 | 16:33:21.1 |      8.571 |
|        15 | 16:33:21.2 |     10.000 |
+-----------+------------+------------+
generator list_scan ['fb4d16b7'] (scan num: 1)

Preparing for a PV Scan

As a general rule, one should always verify that the DAQ is running well in "normal" mode before attempting to run a scan.

Some specific tips:

Make sure all the detectors to be used are configured properly.
Make sure the timing system is configured properly. As of this writing, RIX uses readout groups 2 and 5.
When you're ready to record a scan, don't forget to enable recording before running bluesky_rix.py! In the control GUI, the disk icon has a diagonal line over it when not recording.
Use the "normal" DAQ interface to select the detectors of interest as "active" and assign their readout groups.
Put the DAQ in ALLOCATED or CONNECTED state. Now, you are ready to run bluesky_rix.py.

The rix_bluesky_scan.py script accepts several command line arguments. If you are relying on the default settings, make sure they are correct for your experiment now, not just way back in 2020 when the script was first written.

Code Block

language	text
title	rix_bluesky_scan.py help

usage: rix_bluesky_scan.py [-h] [-p {0,1,2,3,4,5,6,7}] [-C COLLECT_HOST]
                           [-t TIMEOUT] [-c READOUT_COUNT] [-g GROUP_MASK]
                           [--config ALIAS] [--detname DETNAME]
                           [--scantype SCANTYPE] [--record] [-v]

optional arguments:
  -h, --help            show this help message and exit
  -p {0,1,2,3,4,5,6,7}  platform (default 2)
  -C COLLECT_HOST       collection host (default drp-neh-ctl001)
  -t TIMEOUT            timeout msec (default 10000)
  -c READOUT_COUNT      # of events to aquire at each step (default 120)
  -g GROUP_MASK         bit mask of readout groups (default 36)
  --config ALIAS        configuration alias (default BEAM)
  --detname DETNAME     detector name (default 'scan')
  --scantype SCANTYPE   scan type (default 'scan')
  --record              enable recording of data
  -v                    be verbose

Detector Configuration Scans

These scans use the same "step" idea described above for EPICS PV step-scans, but instead alter a detector configuration object on each step. Currently this has been done for the EPIX area detector to take data in the various gain ranges. Python code for this can be found here: https://github.com/slac-lcls/lcls2/blob/master/psdaq/psdaq/app/epixhr_pedestal_scan.py

Script Control of Run Stop/Start

One can control the DAQ (e.g. to stop and start runs on a timer) with scripts like this:

Code Block

language	bash

#!/bin/bash                                                                                      
while [ 1 ]
do
echo going to configured
daqstate -p 0 -P tmo -C drp-neh-ctl001 --state configured
sleep 5
echo going to running
daqstate -p 0 -P tmo -C drp-neh-ctl001 --state running
sleep 600
done

Running Scans with Hutch Python

An example hutch-python scan session in RIX. "rix3" also takes a "--debug" option to increase verbosity. TMO has a similar "tmo3" command.

Code Block

language	text

rix-daq:~> rix3
Loading local disk python env pcds-4.1.4
      _      _____       _   _                 
     (_)    |  __ \     | | | |                
 _ __ ___  _| |__) |   _| |_| |__   ___  _ __  
| '__| \ \/ /  ___/ | | | __| '_ \ / _ \| '_ \ 
| |  | |>  <| |   | |_| | |_| | | | (_) | | | |
|_|  |_/_/\_\_|    \__, |\__|_| |_|\___/|_| |_|
                    __/ |                      
                   |___/                       

INFO     Selected default hutch-python daq platform: 0
INFO     Loading debug tools...

(lines removed for brevity)

In [1]: daq.configure(motors=[sim.fast_motor1, sim.fast_motor2],events=10,record=True)
INFO     configure - configure: 2 motors
Out[1]: ({}, {})

In [2]: RE(bp.scan([daq], sim.fast_motor1, 1, 10, sim.fast_motor2, 1, 10, 5))


Transient Scan ID: 1     Time: 2021-10-20 12:06:21
Persistent Unique Scan ID: '81544aea-5fb7-4017-b03d-a1ea8d15c174'
New stream: 'primary'
+-----------+------------+-------------+-------------+
|   seq_num |       time | fast_motor1 | fast_motor2 |
+-----------+------------+-------------+-------------+
|         1 | 12:06:33.3 |           1 |           1 |
|         2 | 12:06:34.4 |        3.25 |        3.25 |
|         3 | 12:06:35.5 |         5.5 |         5.5 |
|         4 | 12:06:36.6 |        7.75 |        7.75 |
|         5 | 12:06:37.7 |          10 |          10 |
+-----------+------------+-------------+-------------+
generator scan ['81544aea'] (scan num: 1)



Out[2]: ('81544aea-5fb7-4017-b03d-a1ea8d15c174',)

In [3]: quit
rix-daq:control>

These are the parameters that are settable in daq.configure (see these with "daq.configure?" in hutch-python):

Code Block

Signature:
daq.configure(
    *,
    motors=None,
    group_mask=None,
    events=None,
    record=None,
    detname=None,
    scantype=None,
    serial_number=None,
    alg_name=None,
    alg_version=None,
)
Docstring:
Set parameters for scan.

Keyword arguments:
motors -- list of motors, optional
    Motors with positions to include in the data stream
group_mask -- int, optional
    Bit mask of readout groups
motors -- list of motors, optional
    Motors with positions to include in the data stream
group_mask -- int, optional
    Bit mask of readout groups
events -- int, optional
    Number of events per scan point
record -- bool, optional
    Enable recording of data
detname -- str, optional
    Detector name
scantype -- str, optional
    Scan type
serial_number -- str, optional
    Serial number
alg_name -- str, optional
    Algorithm name
alg_version -- list of 3 version numbers, optional
    Algorithm version
File:      /u1/rixopr/conda_envs/pcds-5.0.0/lib/python3.9/site-packages/psdaq/control/BlueskyScan.py
Type:      method

Other hutch-python parameters are settable in this per-hutch configuration file:

Code Block

rix-daq:control> more /cds/group/pcds/pyps/apps/hutch-python/rix/conf.yml 
hutch: rix

# Locate happi database
db: /reg/g/pcds/pyps/apps/hutch-python/device_config/db.json

# Hutch-specific imports
load: rix.beamline

# DAQ interface configuration
daq_type: lcls2

daq_host: drp-neh-ctl001

daq_platform:
  default: 2
rix-daq:control>

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Versions Compared

Old Version 36

New Version 37

Key

Table of Contents
Introduction

On-The-Fly Scans

EPICS PV Step-Scans

Preparing for a PV Scan

Detector Configuration Scans

Script Control of Run Stop/Start

Running Scans with Hutch Python

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Page History

Versions Compared

Old Version 36

New Version 37

Key

Table of ContentsIntroduction

On-The-Fly Scans

EPICS PV Step-Scans

Preparing for a PV Scan

Detector Configuration Scans

Script Control of Run Stop/Start

Running Scans with Hutch Python

Table of Contents
Introduction