Conveyor tracking, Queue Tracking Mode

jschoene

Hi guys,

we would like to use the DSQC 377A in Queue Tracking-Mode.

Reading the Robot ware conveyor tracking manual "3HAC16587-3 Revision D" (german version), I understand that you need to set the parameter

c1PosInJob = 1. In this case, we need to handle the WObj queue our selves. See manual page 87 (paragraph 9.1.2). (Notice c1PosInJob = 0 is the standard case, where the WObj queue is handled on the board - this is not used here.)

Example code from the manual for handling the WObj queue is given on page 90 and reads the following:

------------------------------
[code start]

SetDO c1PosInJobQ, 1;

CONNECT NewObj WITH NewObjOnConvey;
ISignalDI c1NewObjStrobe, high, NewObj;

TRAP NewObjOnConvey
  ObjectPosition1 := GInput(c1Count1FromEnc);
  ObjectPosition2 := GInput(c2Count2FromEnc);
  RETURN;
ENDTRAP

TRAP TrackNewObj
  SetGO c1Count1ToEnc, ObjectPosition1;
  SetGO c1Count2ToEnc, ObjectPosition2;
  WaitTime 0.05;
  PulseDO c1CountToEncStr;
  RETURN;
ENDTRAP

[code end]
------------------------------

This code does work if we pulse a DO, that is interrupt trapped by "TRAP TrackNewObj" and then use the instruction WaitWObj to actually connect to the WObj.

However, here is my question:
I do not fully understand, how we handle the case, if there is no work object yet.
Is it the right way to write a subroutine like (symbolic code)

------------------------------
[code start]

PROC GetWObj
  
  if ( notEmpty(WObjQueue) ) then

    # WObj available: connect
     
    SetGO c1Count1ToEnc, WObjQueue.ObjectPosition1;
    SetGO c1Count2ToEnc, WObjQueue.ObjectPosition2;
    WaitTime 0.05;
    PulseDO c1CountToEncStr;
 
    WaitWObj WObj
 
  else
 
    # handle the case NO WObj available
 
  end

ENDPROC

[code end]
------------------------------

Summed up question:
Which is the professional way of implementing the queue tracking mode? Are there any fully runnable code examples available?

Any help is greatly appreciated.
Thanx,

Jan.