Experimental Physics and
Industrial Control System

"J. Lewis Muir" <[email protected]> · Thu, 08 Nov 2007 18:05:40 -0500

I have found that if a subArray record reads 0 elements into its array,
it sets its INDX field to 0. Is this behavior intended? I would rather
it not change its INDX field in this situation.
As an example, say I read four bytes from a serial connection with an
asyn record. I then want to grab the fourth read byte from the asyn
record's BINP field with a subArray record. So I make the subArray
record's INDX field have the value 3. Now say the asyn record has a
read error and reads 0 bytes from the serial connection. When the
subArray record processes, it sets its INDX field to 0. At this point,
my database is broken because INDX has the wrong index for getting the
fourth byte of the asyn record's BINP field.
I've attached an example database that shows this problem. Run it on an
IOC and run the following commands assuming a PV prefix of "xxx:":
$ caget xxx:FourthByte.INDX
$ caput xxx:ReadFourBytes.PROC 1
$ caget xxx:FourthByte.INDX
In the first caget, INDX will be 3. In the second caget, INDX will be 0.
I've attached a small patch against EPICS 3.14.8.2 base to fix this.
But maybe I'm mistaken and the way it works is how it is supposed to work?
My configuration is:
* Processor: Intel Core Duo
* OS: Mac OS X 10.4.10
* EPICS 3.14.8.2
* synApps 5.2 (with motor 6-2-2 + fixes, asyn 4-8 + fixes, sscan 2-5-6)
Thanks,
Lewis
--
J. Lewis Muir
Software Engineer
CARS/IMCA-CAT
#
#  Parameters:
#    $(P)     PV name prefix (e.g. 17bm:)
#

record(asyn, "$(P)ReadFourBytes") {
  field(PORT, "noexistent")
  field(TMOT, "2.0")
  field(TMOD, "Read")
  field(NRRD, "4")
  field(IFMT, "Binary")
  field(FLNK, "$(P)FourthByte")
}

record(subArray, "$(P)FourthByte") {
  field(INP, "$(P)ReadFourBytes.BINP NPP MS")
  field(FTVL, "CHAR")
  field(MALM, "4")
  field(NELM, "1")
  field(INDX, "3")
}

*** src/rec/subArrayRecord.c.orig	Tue Apr  1 16:02:03 2003
--- src/rec/subArrayRecord.c	Thu Nov  8 16:52:46 2007
***************
*** 314,320 ****
          if (psa->nord <= 0)
          {
             status = -1;
-            psa->indx = 0;
          }
          return(status);
  }
--- 314,319 ----

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System