Ned,
I now have a modified version of your image record working and async
device support for my DataCell board grabbing frames. I am going to
attempt to use the genSub record to connect a subroutine now. Do you
have any example code that shows an implementation of what you discussed
below.
Thanks,
Len
Ned Arnold wrote:
>
> Hey Len,
>
> > Thanks for the reply,
> >
> > A couple of quick questions:
> >
> > What was the intended purpose of the enab and rate fields?
>
> These were implemented as safe guards to "throttle" the transferring of
> the entire image to a client. In my application, the client will fetch
> the image whenever the VAL field of the image record changes (increments).
> So, if ENAB (enable) is set to 0, the VAL field will not increment even if
> something processes the image record. One would set ENAB to 0 if the image is
> known to be invalid (maybe the camera is off!).
>
> The RATE field sets a minimum time between increments of the VAL field.
> If the image record scans at 10 Hz (because of a database flub up) and
> RATE is set to .49, the VAL field will only increment at 2 hertz, thereby
> "throttling" the client's fetching of an image. Set RATE to 0 for
> no throttling.
>
> Both of these are a result of my paranoia of swamping the network with
> image data. Ignore them if you don't have the same fears.
>
> >
> > I understand the vxnm now and I actually have two different versions
> > of your record code. If I add pimg field as you suggest is this just
> > another DBLINK or how do I specify it in the ImageRecord.dbd file?
>
> Marty Kraimer had a better idea than "exporting" the pointer through
> a record field. Your subroutine can find out all the information it
> needs about .L0 (the pointer to the first pixel) by using the database
> access routines described in Chapter 12 of the EPICS IOC Application
> Developer's Guide. Specifically, if you call dbGetPdbAddrFromLink(for INPn)
> (Pg 138) from your subroutine record, you get all the "dbAddr" information
> described on pg 129, including the address of the field. This would allow
> you to find the image without passing any of the image data around. I
> agree that this is probably the best way to meet your need.
>
> For example, if the subroutine record had input links defined for ...
>
> INPA image_record_1.L0
> INPB image_record_1.XRES
> INPC image_record_1.YRES
> INPD image_record_1.SIZE
>
> your analysis routine could find out all the information about the image
> without duplicating any definition of it.
>
> Hope this helps ...
>
> Ned
>
--
____________________________________________________
Leonard J. Reder
Jet Propulsion Laboratory
Interferometry Systems and Technology Section 383
Email: [email protected]
Phone (Voice): 818-354-3639
____________________________________________________
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