RE: Writing mbbo/mbbi text labels using asynPortDriver/areaDetector

[Mark Rivers <rivers@cars.uchicago.edu>]

Hi Tom,

One of the limitations of asyn that you pointed out in your message last year has been that there was no way for drivers to set the values of enum values in records.  In many cases this is not a problem, since the values are known in advance and can be set in the database files.  But, as you described, some drivers need to set the enum values, for example a driver that works with several models of a device, and the choices vary with the model.

I have added a new asyn interface, asynEnum, to address this problem.  This is the definition of the interface.

#########################################
#define asynEnumType "asynEnum"
typedef struct asynEnum {
    asynStatus (*write)(void *drvPvt, asynUser *pasynUser,
                       char *strings[], int values[], int severities[], size_t nelements);
    asynStatus (*read)(void *drvPvt, asynUser *pasynUser,
                       char *strings[], int values[], int severities[], size_t nelements, size_t *nIn);
    asynStatus (*registerInterruptUser)(void *drvPvt, asynUser *pasynUser,
             interruptCallbackEnumStrings callback, void *userPvt,
             void **registrarPvt);
    asynStatus (*cancelInterruptUser)(void *drvPvt, asynUser *pasynUser,
             void *registrarPvt);
} asynEnum;
#########################################

I've modified the bi, bo, mbbi, and mbbo support in devAsynInt32 and devAsynUInt32Digital to query the enum strings from the driver in init_record, if the driver supports the interface.  The driver can control not only the enum strings, but also the values and severities.  The interface also supports callbacks, so drivers can notify device support at run-time when the enums have changed.  For example, selecting a new ADC speed may change the available gains, etc.  When enums are changed at run-time, older channel access clients like medm will not update those widgets immediately, but will if the window is closed and re-opened.


I have made the following additions to asynPortDriver to support this new interface:

An additional interface mask for using in calling the asynPortDriver constructor.
#define asynEnumMask            0x00002000

3 new functions:
virtual asynStatus readEnum(asynUser *pasynUser, char *strings[], int values[], int severities[], size_t nElements, size_t *nIn);
virtual asynStatus writeEnum(asynUser *pasynUser, char *strings[], int values[], int severities[], size_t nElements);
virtual asynStatus doCallbacksEnum(char *strings[], int values[], int severities[], size_t nElements, int reason, int addr);

asynPortDriver::readEnum and writeEnum base class implementations are dummy functions that just return asynError.  Derived classes can implement these functions, typically just readEnum, for drivers that want to set enum values in init_record.

asynPortDriver::doCallbacksEnum handles callbacks to clients when enums change at run-time.

The asyn example/test programs, testAsynPortDriver and testErrors now demonstrate and test the readEnum and doCallbacksEnum functions.

The new interface is committed to Subversion:

https://svn.aps.anl.gov/epics/asyn/trunk/

It will appear in asyn R4-19 soon.  Meanwhile anyone who has time to test it is encouraged to do so.

Thanks,
Mark



-----Original Message-----
From: tom.cobb@diamond.ac.uk [mailto:tom.cobb@diamond.ac.uk] 
Sent: Tuesday, January 04, 2011 8:29 AM
To: Mark Rivers
Cc: tech-talk@aps.anl.gov
Subject: Writing mbbo/mbbi text labels using asynPortDriver/areaDetector

Hi all,

I've been writing an areaDetector driver that will support the majority
of generic GigE Vision cameras, and I've run into a problem. A number of
the parameters supported by the driver are enumerations that vary from
camera to camera. For instance, the TriggerSource enum on one camera may
be ["Internal", "External"], or ["Line1", "Line2", "FixedRate",
"Software"] on another. I could create a database for each camera
containing the correct labels for each parameter, but it would be a lot
neater to get the mbbo/mbbi record to query asynPortDriver for a list of
strings at startup.

Does anyone have any ideas on the neatest approach on this, and some
pointers on where to make the modifications?

Thanks,
Tom Cobb,
Diamond Light Source Ltd.
Diamond House
Harwell Science and Innovation Campus
Didcot
Oxfordshire
OX11 0DE
Tel +44 (0) 1235 778582

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