`PyDMEnumButton` widget change pressed state when the underlaying PV is in closed_loop mode, or disabled

[jesusvasquez333]

Describe the bug A PyDMEnumButton widget connected to EPICS PV allow the user to "press" choices when the underlaying PV is disabled (.DISA = 1), or in "close_loop" mode (.OMSL = closed_loop). A PV under these condition does not change states. However, the widget visually change state even in the underlying PV does not.

Expected behavior I would expect a behavior similar to the EDM's Choice Button widget: When the PV is in these states, the widget does not change state when any choice is pressed.

Steps to Reproduce

• Create, for example, an mbbo PV with some states, and run it on an IOC. In my case I was using a this PV:

record(mbbo, "SIOC:B34:RF13:0:TRIGMODE")
{
    field(DESC, "Trigger mode")
    field(DTYP, "Raw Soft Channel")
    field(PINI, "YES")
    field(ZRST, "Disable")
    field(ONST, "STDBY")
    field(TWST, "ACCEL")
    field(THST, "")
    field(ZRVL, "0")
    field(ONVL, "2")
    field(TWVL, "3")
    field(THVL, "")
    field(DOL,  "SIOC:B34:RF13:0:TRIGMODE_OR CP")
    field(OMSL, "supervisory")
    field(OUT,  "SIOC:B34:RF13:0:MODECFG PP")
    field(VAL,  "")
    info(autosaveFields, "VAL")
}

record(mbbo, "SIOC:B34:RF13:0:TRIGMODE_OR")
{
    field(DESC, "Trigger mode (override)")
    field(PINI, "YES")
    field(ZRST, "Disable")
    field(ONST, "STDBY")
    field(TWST, "ACCEL")
    field(THST, "")
    field(ZRVL, "0")
    field(ONVL, "2")
    field(TWVL, "3")
    field(THVL, "")
    field(ASG,  "Internal")
}

• Create a PyDM display and add a PyDMEnumButton widget, setting its channel to this PV (using the CA protocol).
• At this point, you should be able to select any of the 3 choices.
• Now, for example, set the output mode of this PV to closed_loop:

$ caput SIOC:B34:RF13:0:TRIGMODE.OMSL closed_loop
Old : SIOC:B34:RF13:0:TRIGMODE.OMSL  supervisory
New : SIOC:B34:RF13:0:TRIGMODE.OMSL  closed_loop

• At this point, the PV can not be change via CA:

$ caput SIOC:B34:RF13:0:TRIGMODE ACCEL
Old : SIOC:B34:RF13:0:TRIGMODE       STDBY
New : SIOC:B34:RF13:0:TRIGMODE       STDBY
$ caput SIOC:B34:RF13:0:TRIGMODE Disable
Old : SIOC:B34:RF13:0:TRIGMODE       STDBY
New : SIOC:B34:RF13:0:TRIGMODE       STDBY

• However, if you push choices in the widget, the "pressed" choice changes in the widget: even if the PV does not change state
• If you create a EDM screen with a Choice Button widget connected to this PV, pushing different choices in the widget does not change the "pressed" choice in the widget:

My Platform I'm running the SLAC's official PyDM (1.10.7) and EDM packages install in AFS on lcls-dev3. For the IOC, I was using EPICs base R7.0.3.1-1.0, also from AFS space.

[hhslepicka]

That is a tricky one! Thank you for this report! I am almost sure it is due to the lack of feedback on the put operation on our side. I will think about a possible solution for that.