PURPOSE:

The purpose of this laboratory is to develop an understanding of how shift registers work and can
be applied to control a tracking system.  Parts are inspected in Zone 1 and "tracked" through the
processing line until Zone 5 is reached.  If a bad part is present at Zone 5, it is diverted off of the conveyor
upon activation of a diverting solenoid gate.   Good parts continue downstream.

OBJECTIVES:

After completion of this laboratory exercise you should be able to do the following:

    1.  Explain the theory of how a shift register works;
    2.  Program a shift register into the S7224  OR 214 PLC;
    3.  Address individual bits in the shift register;
    4.  Implement a data bit for storing "inspection" status;
    5.  Use individual register bits to control discrete outputs;
    6.  Develop a "one shot" pulsed input to control the shifting of bits;
    7.  Program counters to keep track of good parts, bad parts, total parts;
    8.  Monitor the status of the plc using a status table.

SYSTEM OPERATION

The system is activated by depressing the start switch which turns on the conveyor motor.  Parts are
equally spaced by a flexible locating fixture on the conveyor.  Parts entering the system at Zone 1 one
are inspected as good (short) or tall (bad) using an optical switch.  A counter keeps track of the total
number of parts inspected.  As the parts move between zones a third optical sensor is used to shift the
data bit stored in the  shift register at position one (indicating good or bad part:  1 = bad, 0 = good).
If a good part is  detected, processing occurs at each successive zone.   However if a bad part is
detected, processing is  suspended as the bad part is tracked to Zone 5.  At this station, bad parts are
diverted off the conveyor and good parts continue downstream.   A second counter keeps track of the
number of bad parts leaving the system.  Parts are equally spaced on the conveyor and "in position"
is detected by an optical sensor within Zone 2.

REQUIREMENTS:

Develop the control logic for the system described.  Your program should be able to do the following:
    1.    Activate the system when the start switch is depressed
    2.    Detected good or bad parts at Zone 1;
    3.    Detect "in position" at Zone 2;
    4.    Turn on a spray nozzle solenoid at Zone 3 ONLY IF A GOOD PART IS PRESENT;
    5.    Turn on a heat element at Zone 4 ONLY IF A GOOD PART IS PRESENT;
    6.    Track bad parts through the system;
    7.    Divert bad parts off the conveyor by activating a solenoid diverter at Zone 5 if a bad part is present;
    8.    Count the number of bad parts;
    9.    Count the number of good parts;
    10.  Count the total number of parts.
    11.  Shut down the system anytime the stop switch is depressed.

Note:  DEVELOP THE  CONTROL LOGIC FOR THE SIEMENS 224/214 PLC in MicroWin32.

Follow the usual format for documenting the laboratory exercise.