Re: Read record field in asynDriver

[Ralph Lange <Ralph.Lange@gmx.de>]

Well,

Using info items, this can be solved outside of ASYN.

If we put info items with the by-channel configuration info into the 
records, we can loop over all records and search for those items when 
initializing the card, and do the by-channel initialization at that 
point. This will be perfectly after the card initialization, but early 
enough (before the db is initialized and processing starts), and the 
info item can be set up to contain exactly the information needed.

Sorry for bothering you,
~Ralph


On 19/02/2015 15:26, Ralph Lange wrote:
> Hi Mark,
>
> We are facing a similar issue:
>
> Our ASYN port driver for a DAQ board is modelling the board and its 
> channels as a multi device, with port=board and addr=channel.
>
> During per-record-instance initialization, the port driver must call 
> the low level card driver with one configuration call per channel, 
> using board number, channel number, and range (record's EGUL, EGUF) as 
> parameters.
>
> What would be your approach for that?
>
> Your intermediate record hack does not work nicely (in addition to 
> being somewhat ugly), as the parameter values would come in too late 
> and separately, and the addr=channel number is not contained in a 
> field of the "main" record.
>
> The driver's connect() is only called once for the port, right?!
> Couldn't that be complemented with a routine that is called once per 
> addr for multi devices, and gets the addr and maybe a pointer to the 
> parameter field of the link that it is being called for? (We'd be 
> happy to cram the necessary low level config params into the link 
> config, and have the driver pull it out.)
> Alternatively, probably cleaner and more flexible, you could allow a 
> special info field for asyn driver configuration options to be added 
> to the record, and pass a a pointer to its string value when calling 
> the driver for each addr.
>
> What do you think?
>
> Thanks for your help,
> ~Ralph
>
>
> On 02/02/2015 23:36, Mark Rivers wrote:
> > There is no direct communicaton possible between the NELM field of 
> > the waveform record and the asyn driver.  However, it is easy to do 
> > using an intermediate longout record, for example:
> >
> > record(longout,"$(P)$(R)NELM1") {
> >      field(DOL,  "$(P)$(R)Waveform1.NELM CP MS")
> >      field(OMSL, "closed_loop")
> >      field(DTYP, "asynInt32")
> >      field(OUT, "@asyn($(PORT),$(ADDR),$(TIMEOUT))WAVEFORM_NELM1")
> > }
> >
> > record(longout,"$(P)$(R)NELM2") {
> >      field(DOL,  "$(P)$(R)Waveform2.NELM CP MS")
> >      field(OMSL, "closed_loop")
> >      field(DTYP, "asynInt32")
> >      field(OUT, "@asyn($(PORT),$(ADDR),$(TIMEOUT))WAVEFORM_NELM2")
> > }
> >
> > These longout records  will process whenever the NELM fields change, 
> > including once at iocInit.
> >
> > They will send the NELM field of the appropriate waveform record to 
> > you driver.  You just need to treat the writes with 2 different 
> > pasynUser->reason values differently.  If it is the one corresponding 
> > to WAVEFORM_NELM1 do one thing, and do something different if it is 
> > for WAVEFORM_NELM2.
> >
> > Mark