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<== Date ==> <== Thread ==>
Subject: RE: How to work with motor record position counts larger than 2147483648?
From: Mark Rivers <[email protected]>
To: "'Sobhani, Bayan'" <[email protected]>, "[email protected]" <[email protected]>
Date: Mon, 22 Jan 2018 23:02:45 +0000

Hi Alex,

 

The problem is that the RRBV field in the motor record is a 32-bit integer:

 

This is from motorRecord.dbd:

 

        field(RRBV,DBF_LONG) {

                prompt("Raw Readback Value")

                special(SPC_NOMOD)

        }

 

The motor driver reads back the theoretical and encoder positions as doubles, but then they is converted to 32-bit integers in devMotorAsyn.c to be compatible with the fields in the record.

 

    if ( pPvt->needUpdate )

    {

        epicsInt32 rawvalue;

 

        rawvalue = (epicsInt32)floor(pPvt->status.position + 0.5);

        if (pmr->rmp != rawvalue)

        {

            pmr->rmp = rawvalue;

            db_post_events(pmr, &pmr->rmp, DBE_VAL_LOG);

        }

 

        rawvalue = (epicsInt32)floor(pPvt->status.encoderPosition + 0.5);

        if (pmr->rep != rawvalue)

        {

            pmr->rep = rawvalue;

            db_post_events(pmr, &pmr->rep, DBE_VAL_LOG);

        }

 

Mark

 

 

 

From: [email protected] [mailto:[email protected]] On Behalf Of Sobhani, Bayan
Sent: Monday, January 22, 2018 4:20 PM
To: [email protected]
Subject: How to work with motor record position counts larger than 2147483648?

 

I am working on adapting the SmarAct MCS motor record driver for the MCS2, which seems to record its position in picometers unlike the MCS’s nanometers.

 

I have the following code in my polling function:

 

Int64_t val = getp(0); //Gets position of channel 0 positioner

printf(“%f\n”,(double) val); //prints -6000093133.000000

setDoubleParam(c_p_->motorEncoderPosition_,(double)val);

setDoubleParam(c_p_->motorPosition_,(double)val);

…

callParamCallbacks();

return asynSuccess;

 

But when I look at the motor record, the RRBV is shown as -2147483648. I looked at asynMotorController.cpp and saw the line:

 

createParam(motorEncoderPositionString,        asynParamFloat64,    &motorEncoderPosition_);

 

Shouldn’t this mean I can write 64-bit floating point values to motorEncoderPosition_ (i.e. larger than 2147483648)? How should I go about working with position counts larger than 2147483648?

 

Alex

Replies:
Re: How to work with motor record position counts larger than 2147483648? Torsten Bögershausen
References:
How to work with motor record position counts larger than 2147483648? Sobhani, Bayan
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