Experimental Physics and
Industrial Control System

Here is my polling function for the MCS2 driver I am developing:

asynStatus SmarActMCS2Axis::poll(bool* moving_p){

        int64_t val;

        comStatus_=getp(channel_,&val);

        if(comStatus_!=asynSuccess){

                *moving_p=false;

               asynPrint(c_p_->pasynUserSelf,ASYN_TRACE_ERROR,"Error reading axis, channel=%d, comstatus=%d!\n", channel_,comStatus_);

                //c_p_ is a pointer to the controller object

                //setIntegerParam(c_p_->motorStatusProblem_,1);

                setIntegerParam(c_p_->motorStatusCommsError_,1);

                callParamCallbacks();

                return asynError;

        }

        val=val/1000;

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

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

        if(is_moving(channel_)==true){

                *moving_p=true;

        }

        else{

                *moving_p=false;

        }

        setIntegerParam(c_p_->motorStatusProblem_,0);

        setIntegerParam(c_p_->motorStatusCommsError_,0);

        setIntegerParam(c_p_->motorStatusMoving_,*moving_p);

        setIntegerParam(c_p_->motorStatusDone_, ! *moving_p);

        callParamCallbacks();

        return asynSuccess;

}

Notice that “setIntegerParam(c_p_->motorStatusProblem_,1);” is commented out because when I uncomment it, it causes the IOC to have a segmentation fault when I attempt to move an axis that is not connected. Surprisingly, “setIntegerParam(c_p_->motorStatusCommsError_,1);” does not cause the IOC to have a segmentation fault, and as expected raises a COMM alarm when I attempt to move an axis that is not connected. motorStatusProblem and motorStatusCommsError are not referenced anywhere else inside my code. What is causing the segmentation fault to occur?

Alex