Experimental Physics and
Industrial Control System

"Mark Rivers" <[email protected]> · Sun, 11 Jul 2010 16:21:13 -0500

Hi Zen,

> You showed me how to initialize a longout record from a hardware register at iocInit time. 
>  I implemented that, as you suggested by creating my version of the virtual function readInt32, and it works fine.

Note that you don't even need to implement your own version of readInt32.  All you need to do is read the value from the hardware register in your constructor and call setIntegerParam with the value.  Then when device longout support calls the asynPortDriver::readInt32 function during initialization it will get the current value, and will get an asynSuccess return.  If you have not called setIntegerParam before iocInit then asynPortDriver::readInt32 will return asynError, and the longout device support will not initialize the record to that value.

> How can I modify the contents of a longout record from the low level driver code at run time?  

> I am developing a low level asyn driver derived from asynPortDriver class and it became of interest to me to do that.  

> I think that I could accomplish this using dbAccess routines, but that seems somewhat inelegant.

I would recommend doing it in the database.  Here is an example of how I do it.  There are 2 longout records, one with soft device support and one with asyn device support.  There is a longin record on the same parameter with SCAN=I/O Intr.  When your driver does setIntegerParam() and callParamCallbacks() this longin record processes.  It writes the value into the soft longout record, which writes it to the asyn longout.  But the asyn longout does not process because of the configuration of SDIS and DISV, so your driver is not called.  This has the effect of synchronizing the longout to the driver value any time the driver changes it.

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: Szalata, Zenon M. [mailto:[email protected]]
Sent: Sun 7/11/2010 3:53 PM
To: Mark Rivers
Cc: [email protected]
Subject: Another asynPortDriver Question

Hi Mark,
You showed me how to initialize a longout record from a hardware register at iocInit time.  I implemented that, as you suggested by creating my version of the virtual function readInt32, and it works fine.

I now have a related question.
How can I modify the contents of a longout record from the low level driver code at run time?  I am developing a low level asyn driver derived from asynPortDriver class and it became of interest to me to do that.  I think that I could accomplish this using dbAccess routines, but that seems somewhat inelegant.

Thanks in advance,
Zen

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System