Rough flyscan

[gfabbris]

We did some testing on running a "rough" flyscan that is completely managed by Bluesky, meaning that there is no external synchronization. First, the IOC motor setup needs to be modified to increase the readout speed:

From @jwkim-anl :

in vme.cmd file, find 'oms58Setup(7, 0x1000, 190, 5, 10)' and change '10' to '60' and reboot. It may do the 60 Hz update which means 16.7 ms update.

So we can have a plan that sends the motor to the final position and then reads the data as fast as it can. Based on our preliminary tests, a bluesky.plan_stubs.trigger_and_read can process 1 scaler + 1 motor in around 40 msec, with scaler counting for 10 msec. See plan and data below.

Some of what remains to be done:

• Organize plan. Setup metadata. Allow for something other than trigger_and_read?
• Can area detectors be added? Using EPICS to trigger tends to be slow (> 100 msec).
• It'd be better to handle the motor velocity at staging, but that would involve tweaking the .unstage of EpicsMotor, for example: https://github.com/APS-4ID-POLAR/polar_instrument/blob/50961b8ce4740430f07cc7cd64f791a746b96519/instrument/devices/nanopositioner.py#L13

from bluesky.plan_stubs import trigger_and_read
from bluesky.plans import count
from bluesky.preprocessors import stage_decorator, run_decorator
from bluesky.utils import Msg
from instrument.collection import abs_set, mv

def flyscan(detectors, motor, start, end, speed, delay=0):

    yield from mv(motor, start)

    # change this to staging
    speed_stash = yield from rd(motor.velocity)
    yield from mv(motor.velocity, speed)

    if per_shot is None:
        per_shot = trigger_and_read

    devices = list(detectors) + [motor]

    @stage_decorator(devices)
    @run_decorator(md={})
    def inner_count():
        yield from abs_set(motor.user_setpoint, end)
        # yield from sleep(0.1)
        _motor_moving_stash = False
        while True:
            if (_motor_moving_stash is True) and (motor.moving is False):
                break
            _motor_moving_stash = motor.moving
            yield Msg('checkpoint')
            yield from trigger_and_read(devices)
            yield from sleep(delay)  # TODO: tweak to account for how long this took?

        yield from mv(motor, end)

    return (yield from inner_count())
    yield from mov(motor.velocity, speed_stash)

[gfabbris]

A couple of extra ideas:

• The scaler might be able to provide the trigger to the area detector. Or maybe the other way around.
• Make a monitor stream with the motor position. This way it will collect the position as fast as it can, and we can use it to better understand the position during the data collection.

[gfabbris]

Some extra tweaks

def flyscan(detectors, motor, start, end, speed, delay=0, per_shot=None):

    yield from mv(motor, start)

    # change this to staging
    speed_stash = yield from rd(motor.velocity)
    print(speed_stash)
    yield from mv(motor.velocity, speed)

    if per_shot is None:
        per_shot = trigger_and_read

    devices = list(detectors) + [motor]

    @stage_decorator(devices)
    @monitor_during_decorator([motor])
    @run_decorator(md={})
    def inner_count():
        yield from abs_set(motor.user_setpoint, end)
        _motor_moving_stash = False
        while True:
            t0 = time()
            if (_motor_moving_stash is True) and (motor.moving is False):
                break
            if (_motor_moving_stash is False) and (motor.moving is True):
                _motor_moving_stash = True
            yield Msg('checkpoint')
            yield from trigger_and_read(devices)
            d = delay - (time() - t0)
            if d > 0:
                yield from sleep(d)

        yield from mv(motor, end)
        yield from mv(motor.velocity, speed_stash)

    return (yield from inner_count())

[gfabbris]

To get the .read() timestamps: cat[-1].primary.timestamps.read()

[gfabbris]

We will need to tweak the detector trigger

• Change the stage_sigs to the appropriate values
• Include a trigger condition option that does not wait for the detector in fly mode (in the trigger method).

[gfabbris]

Using the ACS controller, the fastest EPICS updated the position was ~200 Hz. This was done by only changing the MOVING_POLL to 0.001 (smaller numbers didn't make it faster), this can be added as an option here: https://github.com/epics-motor/motorAcsMotion/blob/f99eda1de1cdb43fae1f9c8b9f9d763f5aceca4b/iocs/acsMotionIOC/iocBoot/iocAcsMotion/AcsMotion.cmd#L4