Experimental Physics and
Industrial Control System

Marty Kraimer <[email protected]> · Tue, 29 Nov 2005 08:16:56 -0600

Bruins, Stefan wrote:
I presume this change has to be made in the "devSupportGpib.c" file of the

asyn driver in the function "writeIt"? Will a make of the ASYN module be

sufficient or must I run the makeSupport command a second time (this may be

a stupid question but I'm pretty new to EPICS/ASYN etc...)

No devSupportGpib.c does not need to be changed.
What you need to do is implement GPIBCVTIO. The devGpib documentation
states:
GPIBCVTIO
 Supports record types:
   ai, ao, bi, bo, event, longin.longout, mbbi, mbbo, mbbiDirect,
   mmboDirect, stringin, stringout, waveform.
   All I/O is done by the |convert| routine, which must be defined.
   |convert| is called by a callback routine and thus can make an
   arbitrary number of calls to low level drivers. It is passed the
   address of |gpibDpvt| which contains the information needed to call
   the low level drivers: |asynCommon, asynOctet, and asynGpib.| Note
   that | asynGpib| may not be present, i.e. |pasynGpib| is null.
   |gpibDpvt| also contains a field |pupvt| which can be used by the
   convert routine. Is is initialized to null. The macro |gpibCmdGet|
   can be used to get the address of |gpibCmd| which contains other
   usefull information.
Your convert routine can start something like:
static int myConvert(struct gpibDpvt *pgpibDpvt, int P1, int P2, char **P3)
{
 asynUser *pasynUser = pgpibDpvt->pasynUser;
 gpibCmd *pgpibCmd = gpibCmdGet(pgpibDpvt);
 asynOctet *pasynOctet = pgpibDpvt->pasynOctet;
 void *asynOctetPvt = pgpibDpvt->asynOctetPvt;
 asynStatus status;

Look in devSupportGpib.h for the definitions of gpibCmd, which contains
the info in the gpibCmd in your source code.
I think Eric Norum has an example of how to implement GPIBCVTIO.
Marty Kraimer

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System