Experimental Physics and
Industrial Control System

"Mark Rivers" <[email protected]> · Thu, 11 Feb 2010 07:51:55 -0600

Hi Hinko,

This is a classic problem of having more than one mechanism for driving an output, and keeping the output PV up-to-date.

Here is a database fragment that handles this logic (thanks to Tim Mooney for this).

FileNumber is the output record, the equivalent of the mbbo record in your case.  Note that it uses soft device support, it does not talk directly to the hardware.  FileNumber_RBV is the input record, the equivalent of the mbbi record in your case.  In my case it it I/O Intr scanned, i.e. it processes when the hardware driver does a callback to device support, but it could also be periodically scanned. There are 2 additional records required.  FileNumber_write is the record that actually talks to the hardware.  FileNumber_Sync is a record that copies the readback value from FileNumber_RBV to FileNumber, but WITHOUT causing the value to be written to the hardware.  It works because the FileNumber_write record has scan disabled if the FileNumber_sync record is processing (PACT=1).  With this logic FileNumber will correctly reflect the actual state of the hardware, and it can also be written to change the hardware.

record(longout, "$(P)$(R)FileNumber")
{
    field(PINI, "YES")
    field(OUT, "$(P)$(R)FileNumber_write PP")
    field(VAL, "1")
}
record(longout, "$(P)$(R)FileNumber_write")
{
    field(SDIS, "$(P)$(R)FileNumber_Sync.PACT")
    field(DISV, "1")
    field(DTYP, "asynInt32")
    field(OUT, "@asyn($(PORT),$(ADDR),$(TIMEOUT))FILE_NUMBER")
}
record(longin, "$(P)$(R)FileNumber_RBV")
{
    field(DTYP, "asynInt32")
    field(INP,  "@asyn($(PORT),$(ADDR),$(TIMEOUT))FILE_NUMBER")
    field(SCAN, "I/O Intr")
    field(FLNK, "$(P)$(R)FileNumber_Sync")
}
record(longout, "$(P)$(R)FileNumber_Sync")
{
    field(DOL,  "$(P)$(R)FileNumber_RBV NPP")
    field(OMSL, "closed_loop")
    field(OUT,  "$(P)$(R)FileNumber PP")
}

Mark

________________________________

From: [email protected] on behalf of Hinko Kocevar
Sent: Thu 2/11/2010 6:27 AM
To: [email protected]
Subject: MBBO update

Hi,

I'm using mbbo record type that provides 5 values/strings. When mbbo
record is controlled from EDM panel using Radio Box I can set the record
value to desired state.

If the state changes in the underlying software my mbbo record does not
update the value - eg. Radio Box button that was last pressed remains
selected in the EDM panel, while actual state changed.

How can this be done?

Providing mbbi record with same PORT and ADDR as mbbo, I can see that
the state in mbbi record updates as soon as the underlying software
changes the value. But this does not update the mbbo record, though..

Here is the mbbo record:

record(mbbo, "$(DEVICE)SWITCH") {
        field(DTYP, "asynInt32")
        field(OUT, "@asyn($(PORT), 0, 1.0)")
        field(ZRVL, "0")
        field(ONVL, "1")
        field(TWVL, "2")
        field(THVL, "3")
        field(FRVL, "4")
        field(ZRST, "MANUAL")
        field(ONST, "AUTO")
        field(TWST, "AVERAGING")
        field(THST, "COMPENSATING")
        field(FRST, "AVE & COMP")
        field(PINI, "YES")
}

Best regards,
Hinko

--
Hinko Kocevar
Technical support software engineer
Instrumentation Technologies
Velika pot 22, SI-5250 Solkan - Slovenia
T:+386 5 3352600, F:+386 5 3352601
mailto: [email protected]

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Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System