Re: Read record field in asynDriver

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

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