External data record selection22711.1.2 External data record selectionApplication:One of eight various workpieces should be made available at a data collection station. The number of thedesired workpiece is set using a BCD selector switch. The transportation process is then triggered by astarting pulse.Assignments:station7removalstationstation6station5station4station3station2station1station0+960 +840 +720 +600 +480 +360 +240 +120 0 -60workpiece pick-upThe horizontal movement is implemented using an NC axis controlled by COMPAX. A pneumatic cylinder,which is controlled by COMPAX using a double solenoid valve, raises and lowers the workpiece pick-up.COMPAX performs all the functions required without superordinate control.Wiring up the digital inputs and outputs:I1I2I5I6I10I11I12I13O7O8I9I14I15I16search MZstartstopBCD-switchI7I8pick-up liftedpick-up loweredlowerpick-upliftpick-upevaluation byexternal callingof command linesremovalstation empty124BCD+24V +24V+24VCOMPAX+24VComments:♦ The inputs I9, I14, I15 and I16 have to be placed on GND or left open.♦ The BCD switch has eight settings. The outputs are encoded with binary.♦ The "Data collection station empty" switch is closed when the data collection station is closed. The switchoperation prevents the workpiece pick-up being lowered for as long as there is a workpiece in the datacollection station.Function:The first event after COMPAX has been started is the approaching of the data collection station. If theworkpiece pick-up is not lowered, the assumption is made that there is still a workpiece in the workpiecepick-up. This is deposited in the data collection station by lowering the workpiece pick-up. The system is nowready for the first transportation process.
