Experimental Physics and
Industrial Control System

Andrew Johnson <[email protected]> · Mon, 8 Sep 2014 17:06:52 -0500

Hi Eric,

On 09/08/2014 03:49 PM, Eric Norum wrote:
> I have a number of mbboDirect records like:
> 
> record(mbboDirect, "$(P)$(R)EVR:event12trig") {
>     field(DESC, "Extraction pre-trigger")
>     field(DTYP, "asynUInt32Digital")
>     field(OUT,  "@asynMask($(PORT) 0x30C 0xFF 0)")
>     field(NOBT, "8")
>     field(MASK, "0xFF")
> }

That MASK setting will be over-written, the mbboDirect::init_record()
routine in Base 3.14 always calculates MASK from NOBT. In 3.15 you can
set it yourself if you want to use non-contiguous I/O bits.

> The IOC starts up and reads back the initial value of this record properly.
> The *first* caput to the record (I’ve tried from EDM and from caput)
> writes the readback value again, not the value from the client.
> Subsequent caputs do write the value from the client.  It’s only the
> first operation that uses old data.
> 
> Is this a known problem? 

Have you monitored the values in the B<n> fields as well as the VAL
field during the above process?

The 3.14 versions of the mbb*Direct records were a bit of a mess, which
I have cleaned up for 3.15 but changed their behaviour slightly. The
3.14 versions didn't always convert the current value between B<n> and
VAL, especially after an initial readback or if you changed the value of
OMSL at runtime. Setting OMSL to closed_loop effectively disables the
B<n> fields since reading DOL provides an already-packed bit-set in the
VAL field.

If the device support's init_record() routine returns 0 the record will
shift RVAL by SHFT bits into VAL, but the 3.14 version does not set the
B<n> fields at all from the result. In 3.15 it will set the B<n> fields
if OMSL is supervisory.

In the process() routine the output value gets constructed from the B<n>
fields when OMSL is supervisory. Writing to the B<n> fields calls
special() which also reconstructs VAL from the B<n> fields when OMSL is
supervisory.

I tried to make everything behave sensibly in the 3.15 version, so
changing OMSL causes the record to convert between the B<n> and VAL
fields properly. Mark's changes to the Asyn device support should be
compatible with the 3.15 version of the record.

- Andrew
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Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System