Experimental Physics and
Industrial Control System

Hello EPICS-community,

 

I'm trying to write an EPICS-motor device support for the PEGASUS Rotation- and Linear-Stages from Micos. I'm using the Hydra and Corvus motor-support from the main EPICS-motor module as a template.

 

I have the following problem when writing the homing sequence for the Rotation-stages: after sending the homing-command string

 

    sprintf(pC_->outString_, "1 0 %i setsw 1 1 %i setsw 1 0 %i sncal", (axisNo_ + 1), (axisNo_ + 1), (axisNo_ + 1));
    pC_->writeController();

 

I need to wait until reference-drive finished aka. the motor stopped, so I can switch off the Limit-switches with the following command:

 

    sprintf(pC_->outString_, "2 0 %i setsw 2 1 %i setsw", (axisNo_ + 1), (axisNo_ + 1));

    pC_->writeController();

 

So far I could resolve this problem by implementing a while loop with an epicsThreadSleep(1.) asking the controller about its moving bit and once it set to 1 (done), execute the desired command. Here is my complete code of the homing function:

 

asynStatus SMCpegasusAxis::home(double baseVelocity, double slewVelocity, double acceleration, int forwards)
{
  asynStatus status;
  int done = 0;
  int axisStatus = -1;
  double position = 0.0;
  // static const char *functionName = "SMCpegasusAxis::home";

  status = sendAccelAndVelocity(acceleration, slewVelocity);

  if (forwards) {
    sprintf(pC_->outString_, "1 0 %i setsw 1 1 %i setsw 1 0 %i sncal", (axisNo_ + 1), (axisNo_ + 1), (axisNo_ + 1));
    pC_->writeController();
   
    // Read the status of this motor
    sprintf(pC_->outString_, "%i nst", (axisNo_ + 1));
    pC_->writeReadController();
    // The response string is an int
    axisStatus = atoi( (char *) &pC_->inString_);
   
    do
    {  
        // Read the current motor position
        sprintf(pC_->outString_, "%i np", (axisNo_ + 1));
        pC_->writeReadController();
        // The response string is a double
        position = atof( (char *) &pC_->inString_);
        setDoubleParam(pC_->motorPosition_, (position / axisRes_) );
        setDoubleParam(pC_->motorEncoderPosition_, (position / axisRes_) );
       
        // Read the status of this motor
        sprintf(pC_->outString_, "%i nst", (axisNo_ + 1));
        pC_->writeReadController();
        // The response string is an int
        axisStatus = atoi( (char *) &pC_->inString_);
       
        // Check the moving bit
        done = !(axisStatus & 0x1);
        setIntegerParam(pC_->motorStatusDone_, done);
        setIntegerParam(pC_->motorStatusMoving_, !done);
       
        epicsThreadSleep(1.);
    } while (done == 0);
   
    //epicsThreadSleep(3.);
    sprintf(pC_->outString_, "2 0 %i setsw 2 1 %i setsw", (axisNo_ + 1), (axisNo_ + 1));
  } else {
    //still ToDo the Home Run backward
  }
  status = pC_->writeController();
  return status;
}

 

 

Having a while-loop with an threadSleep is kind of bad coding I think, so I'm wondering if someone knows a better solution?

 

PS: I'm also trying to update the motor position during the while-loop (it is the "// Read the current motor position" passage). I see the correct position in the asyn communication but the .RBV value of the motor record won't update. I guess, this can only be done from the poll-function?

 

Best regards

Michael

 

 

Michael Sintschuk
Bundesanstalt für Materialforschung und –prüfung (BAM)
8.5 Mikro-ZfP

Unter den Eichen 87
12205 Berlin
GERMANY

P: +49 30 8062-15063 (BESSY, Adlershof)

P: +49 30 8104-4065 (BAM, Steglitz)
michael.sintschuk at bam.de