Behavior when using `bps.trigger_and_read([det1, det2])`

[st3107]

Hi, I am a user of the this package. I have a question of the behavior of this dark preprocessor. If I use the dark plan shown in the documents and create two dark preprocessor for det1 and det2 separately and use the dark preprocessor on the generator returned by the function below.

def take_two_images_at_the_same_time():
    return bpp.pchain(
        bps.mv(shutter, "open"),
        bps.stage(det1),
        bps.stage(det2),
        bps.trigger_and_read([det1, det2]),
        bps.unstage(det2),
        bps.unstage(det1),
        bps.mv(shutter, "closed")
    )

I think it causes the shutter to close at the time right after the det1 is triggered to collect the light frame. I wonder if this will make det1 collect frames when there is no x-ray on the detector?

Here, I print out the messages yield from the preporcessed generator. It shows that the shutter is closed after the det 1 is triggered. The shutter is turned to closed because it is preparing for collecting dark for det2.

set        | shutter    | open                 | group: 3c22dfcd-a081-44e3-b6f9-fa7c1e34983e
wait       |            |                      | group: 3c22dfcd-a081-44e3-b6f9-fa7c1e34983e
stage      | det1       |                      |                     
stage      | det2       |                      |                     
set        | shutter    | closed               | group: 776fbf20-cad4-4b61-8837-ef3805fd26b6
wait       |            |                      | group: 776fbf20-cad4-4b61-8837-ef3805fd26b6
unstage    | det1       |                      |                     
stage      | det1       |                      |                     
trigger    | det1       |                      | group: bluesky-darkframes-trigger
wait       |            |                      | group: bluesky-darkframes-trigger
unstage    | det1       |                      |                     
stage      | det1       |                      |                     
set        | shutter    | open                 | group: 97da8bae-a3e5-433a-b2b3-7429fe6aee91
wait       |            |                      | group: 97da8bae-a3e5-433a-b2b3-7429fe6aee91
stage      | det1       |                      |                     
trigger    | det1       |                      | group: bluesky-darkframes-trigger-e6679b
wait       |            |                      | group: bluesky-darkframes-trigger-e6679b
create     |            |                      |                     
read       | det1       |                      |                     
save       |            |                      |                     
unstage    | det1       |                      |                     
trigger    | det1       |                      | group: trigger-e083e1
set        | shutter    | closed               | group: 687a0d5e-9ece-4a98-bbc9-271d9564b13a
wait       |            |                      | group: 687a0d5e-9ece-4a98-bbc9-271d9564b13a
unstage    | det2       |                      |                     
stage      | det2       |                      |                     
trigger    | det2       |                      | group: bluesky-darkframes-trigger
wait       |            |                      | group: bluesky-darkframes-trigger
unstage    | det2       |                      |                     
stage      | det2       |                      |                     
set        | shutter    | open                 | group: 18ca7f05-4c65-4d6a-90a0-fff3a7f7462a
wait       |            |                      | group: 18ca7f05-4c65-4d6a-90a0-fff3a7f7462a
stage      | det2       |                      |                     
trigger    | det2       |                      | group: bluesky-darkframes-trigger-34a31e
wait       |            |                      | group: bluesky-darkframes-trigger-34a31e
create     |            |                      |                     
read       | det2       |                      |                     
save       |            |                      |                     
unstage    | det2       |                      |                     
trigger    | det2       |                      | group: trigger-e083e1
wait       |            |                      | group: trigger-e083e1
create     |            |                      |                     
read       | det1       |                      |                     
read       | det2       |                      |                     
save       |            |                      |                     
unstage    | det2       |                      |                     
unstage    | det1       |                      |                     
set        | shutter    | closed               | group: 176938b5-d1d5-43bd-80ea-e8cfe4d97718
wait       |            |                      | group: 176938b5-d1d5-43bd-80ea-e8cfe4d97718

[tacaswell]

If there are two pre-processors they do not know about each other so it makes in very likely you will get confilcts like this. I think the solution is to make the preprocessor take a list of detector and make sure it handles the whole set in a coherent way.