Experimental Physics and
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<== Date ==>		<== Thread ==>

Subject:	RE: aSub debug output
From:	"Daykin, Evan via Tech-talk" <tech-talk at aps.anl.gov>
To:	"Johnson, Andrew N." <anj at anl.gov>, Michael Davidsaver <mdavidsaver at gmail.com>
Cc:	EPICS tech-talk <tech-talk at aps.anl.gov>
Date:	Thu, 3 Dec 2020 17:16:54 +0000

Oh right! I forgot about dbcar. I used that a long time ago and forgot about it. That should do nicely. The inputs to my specific case are already MS, which implies MSI, correct? Maybe I just wasn’t paying enough attention and my record was in INVALID/LINK state.

From: Johnson, Andrew N. <anj at anl.gov>
Sent: Wednesday, December 2, 2020 6:19 PM
To: Michael Davidsaver <mdavidsaver at gmail.com>
Cc: Daykin, Evan <daykin at frib.msu.edu>; EPICS tech-talk <tech-talk at aps.anl.gov>
Subject: Re: aSub debug output

[EXTERNAL] This email originated from outside of FRIB

On Dec 2, 2020, at 2:39 PM, Michael Davidsaver <mdavidsaver at gmail.com> wrote:

On 12/2/20 11:42 AM, Daykin, Evan via Tech-talk wrote:

Hi again and thank you all for your suggestions.

I spent some time creating a minimal example, and it behaves, of course, as you all said it does – a simple printf works. The problem is that one of my input links was not resolved, so it did not call the subroutine. I didn’t think of this possibility since TPRO showed the record processing, but Martin pointed me to the documentation where it says:

· If all input-link fetches succeeded, call the routine specified by SNAM.

Now my question becomes: is there a field that can be set such that this failure is not silent, e.g. raise LINK alarm or output some error message indicating which fetch failed?

Not a field, but you can (and imo. should) add the "MSI" modifier to all of your links.

I don’t think Evan needs to set MSI for the record to go into an INVALID/LINK alarm state if one or more of the links isn’t connected, that should be happening anyway. This example uses a subRecord but the same rules apply, the subroutine isn’t called if any of the input links aren’t connected:

woz$ softIoc -x anj

Starting iocInit

############################################################################

## EPICS R3.15.8.1-DEV

## EPICS Base built Nov 25 2020

############################################################################

iocRun: All initialization complete

epics> dbl

anj:BaseVersion

anj:exit

epics> dbpr anj:exit 1

A: 0 ADEL: 0 ASG: B: 0

BKPT: 00 BRSV: NO_ALARM C: 0 D: 0

DESC: Exit subroutine DISA: 0 DISP: 0

DISS: NO_ALARM DISV: 1 DTYP: <nil> E: 0

EGU: EVNT: F: 0 FLNK:CONSTANT 0

G: 0 H: 0 HHSV: NO_ALARM HIGH: 0

HIHI: 0 HOPR: 0 HSV: NO_ALARM HYST: 0

I: 0 INAM: INPA:CONSTANT INPB:CONSTANT

INPC:CONSTANT INPD:CONSTANT INPE:CONSTANT INPF:CONSTANT

INPG:CONSTANT INPH:CONSTANT INPI:CONSTANT INPJ:CONSTANT

INPK:CONSTANT INPL:CONSTANT J: 0 K: 0

L: 0 LLSV: NO_ALARM LOLO: 0 LOPR: 0

LOW: 0 LSV: NO_ALARM MDEL: 0 NAME: anj:exit

PACT: 0 PHAS: 0 PINI: NO PREC: 0

PRIO: LOW PUTF: 0 RPRO: 0 SCAN: Passive

SDIS:CONSTANT SEVR: INVALID SNAM: exit STAT: UDF

TPRO: 0 TSE: 0 TSEL:CONSTANT UDF: 1

UDFS: INVALID VAL: 0

epics> dbpf anj:exit.INPA this-is-not-a-real-pv

DBR_STRING: "this-is-not-a-real-pv NPP NMS"

epics> dbpf anj:exit.PROC 1

DBR_UCHAR: 1 0x1

epics> dbpr anj:exit 1

A: 0 ADEL: 0 ASG: B: 0

BKPT: 00 BRSV: NO_ALARM C: 0 D: 0

DESC: Exit subroutine DISA: 0 DISP: 0

DISS: NO_ALARM DISV: 1 DTYP: <nil> E: 0

EGU: EVNT: F: 0 FLNK:CONSTANT 0

G: 0 H: 0 HHSV: NO_ALARM HIGH: 0

HIHI: 0 HOPR: 0 HSV: NO_ALARM HYST: 0

I: 0 INAM:

INPA:CA_LINK this-is-not-a-real-pv NPP NMS INPB:CONSTANT

INPC:CONSTANT INPD:CONSTANT INPE:CONSTANT INPF:CONSTANT

INPG:CONSTANT INPH:CONSTANT INPI:CONSTANT INPJ:CONSTANT

INPK:CONSTANT INPL:CONSTANT J: 0 K: 0

L: 0 LLSV: NO_ALARM LOLO: 0 LOPR: 0

LOW: 0 LSV: NO_ALARM MDEL: 0 NAME: anj:exit

PACT: 0 PHAS: 0 PINI: NO PREC: 0

PRIO: LOW PUTF: 0 RPRO: 0 SCAN: Passive

SDIS:CONSTANT SEVR: INVALID SNAM: exit STAT: LINK

TPRO: 0 TSE: 0 TSEL:CONSTANT UDF: 1

UDFS: INVALID VAL: 0

Note that in the second dbpr output SEVR: INVALID STAT: LINK show that the record is in alarm state because the INPA field wasn’t connected. How you might flag that to a human when it happens is a different question though, records go into alarm state all the time and never announce that on the IOC console. Maybe some other parts of the database or its clients need to monitor the record’s alarm state if this situation can arise and needs to be known about?

Note that there is an iocsh command which tells you about any unconnected CA links in the database:

epics> dbcar

CA links in all records

Total 1 CA link; 0 connected, 1 not connected.

0 can't read, 0 can't write. (0 disconnects, 0 writes prohibited)

epics> dbcar * 1

CA links in all records

anj:exit.INPA --> this-is-not-a-real-pv (0, 0)

Total 1 CA link; 0 connected, 1 not connected.

0 can't read, 0 can't write. (0 disconnects, 0 writes prohibited)

If you have devIocStats loaded that has PVs that report the connected and disconnected counts.

- Andrew

Complexity comes for free, simplicity you have to work for.

References:: aSub debug output Daykin, Evan via Tech-talk; Re: aSub debug output Johnson, Andrew N. via Tech-talk; RE: aSub debug output Daykin, Evan via Tech-talk; Re: aSub debug output Michael Davidsaver via Tech-talk; Re: aSub debug output Johnson, Andrew N. via Tech-talk

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Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System