Singapore Polytechnic

Singapore PolytechnicSchool of Mechanical and Aeronautical EngineeringPROGRAMMABLE LOGICAL CONTROLLERS MINI-PROJECT REPORTCOMMISSIONING FESTO MODULAR PRODUCTION SYSTEM (MPS-PLUS)TESTING STATION

NameAdmission NoClass

MYO PYAE SONE1148697DMRO/FT/3A/01

CONTENTS1. System Specifications of the whole production process

2. System specifications of TESTING STATION

3. Final Sequential Function Chart

4. Proposal of the communication between Distribution Station and Processing Station

5. Troubleshooting

6. Recommendations

7. Conclusions

8. Appendix-A Final Printed Ladder Diagram

9. Appendix-B Logbook

1. System Specifications of the whole production process

1.1 DISTRIBUTION STATION

The front panel of the DISTRIBUTION station has the following panel buttons: Start, Reset, Magazine Empty, Stop and Auto/Manual. Several parts are held in the IN-magazine barrel. If the Auto/Manual switch is in Manual, each time when you press the START button, just one of the following actions will be executed:

(1) Eject one part.

(2) Transfer part to the TESTING station (to the OUT-magazine) by the rotating arm.1.2 TESTING STATION

The front panel of the TESTING station has the following panel buttons: Start, Reset, Adjusting, Stop and Auto/Manual. The lift must always be at the lower position. The part will be placed on the lift by the rotating arm of the DISTRIBUTION station. Check with your lecturer which colour and which material of the two parts is to be processed and which other part on the lift is to be rejected. If the Auto/Manual switch is in Manual, each time when you press the START button, just one of the following actions will be executed:

(1) Check the part for colour and material by means of the photoelectric, capacitive and inductive sensors.

(2) Raise the lift only if it is the correct part, or else skip this step.

(3) Eject the part.1.3 PROCESSING STATION

The front panel of the PROCESSING station has the following panel buttons: Start, Reset, Not OK and Auto/Manual. Two colour parts from the TESTING station will come into the entry position. The RESET button is assigned to indicate the colour of the part in the entry position. If the RESET button is NOT pressed, it will denote 1st colour part and if the RESET button is pressed, it will denote 2nd colour part. If the Auto/Manual switch is in Manual, each time when you press the START button (and whether with RESET button or NOT) you will do just one of the following steps in the sequence as indicated below. In Manual mode, you will process only one part at a time. (1) Rotate the table to the next position.

(2) Part will be clamped at the drilling position using a single acting cylinder and then a hole is drilled by lowering the drill and then raising the drill.

(3) Rotate the table to the next position.

(4) Check the depth of the hole in the checking position. During the checking if the part is found to be faulty, blink the NOT OK light continuously, or else it should be off.

(5) Rotate the table to the next position.1.4 HANDLING STATION

The front panel of the HANDLING station has the following panel buttons: Start, Reset, Position, Stop and Auto/Manual. The POSITION button is assigned to indicate the colour of the part. If the POSITION button is NOT pressed, it will denote 1st colour part and if the POSITION button is pressed, it will denote 2nd colour part. By using the panel lights you must indicate the colour of the part being sent to the SORTING station. If the Auto/Manual switch is in Manual, when the START button is pressed, the rotating arm will pick up the part from the PROCESSING station (exit position) and transfer to a conveyor belt in the SORTING station. If RESET button and START button are pressed together, the rotating arm will pick up the part from the PROCESSING station (exit position) and reject it in the reject slide (chute) and at the same time the RESET panel light will blink.1.5 SORTING STATION

The front panel of the SORTING station has the following panel buttons: Start, Reset, Position, Stop and Auto/Manual. The part will be placed on the conveyor belt by the HANDLING station. If the Auto/Manual switch is in Manual, when the START button is pressed along with one of the following buttons as shown below, the conveyor belt will start. The part is then channeled to one of the three retainers to sort them accordingly. Each panel button is assigned to indicate the colour of the part as shown below: (a) RESET button Black part. (b) POSITION button Silver part.

(c) STOP button Orange part. You are required to place the BLACK part in the first retainer and the SILVER part in the second retainer and ORANGE part in the third retainer. At any instance you must be able to show (in the program) the number of parts in each retainer and the total number of parts received. If the Auto/Manual switch is in Auto, when the Start button is pressed once, the process will run continuously and sort the parts as they arrive and place them in different retainers depending on the above buttons being pressed. You will use the panel lights to indicate whether there is a part in that retainer. If no part is in that retainer, the corresponding panel light will be off. Also you have to propose a method to communicate with the HANDLING station in writing in your report.2. System Specifications of TESTING STATION

Function Specifications

TESTING STATION

The front panel of the TESTING station has the following panel buttons: Start, Reset, Adjusting, Stop and Auto/Manual. The lift must always be at the lower position. The part will be placed on the lift by the rotating arm of the DISTRIBUTION station. Check with your lecturer which color and which material of the two parts is to be processed and which other part on the lift is to be rejected. If the Auto/Manual switch is in Manual, each time when you press the START button, just one of the following actions will be executed:

(1) Check the part for color and material by means of the photoelectric, capacitive and inductive sensors. (2) Raise the lift only if it is the correct part, or else skip this step.

(3) Eject the part.

If the Auto/Manual switch is in Auto, when the START button is pressed once, the above steps will execute in the same sequence every time a part arrives on the lift from the DISTRIBUTION station. The STOP button will stop the sequence at any time to pause (freeze) the sequence and pressing the START button will resume the sequence. After checking the part, the following lights will turn on corresponding to its color:

(a) Black part START panel light.

(b) Silver part RESET panel light.

(c) Orange part ADJUSTING panel light.

Whenever a part is rejected, the corresponding panel light should blink. Also you have to propose a method to communicate with the DISTRIBUTION station and PROCESSING station in writing in your report.3.0 Final Sequential Function Chart

4. Proposal of the communication between Distribution Station and Processing Station4.1 Receiving the part from DISTRIBUTION STATION

The TESTING STATION will receive the part sent from the rotating arm of the DISTRIBUTION STATION. The part will be placed on the lift by the arm. So testing station must be installed where the lift of it locates at the end of the rotating arm so that the part would be placed within a specified range.4.2 Communicating with PROCESSING STATION

The Testing Station will choose two materials of different colors and send to the Processing Station. That Station will sense and process the piece one by one. So the output of testing station should be connected to the specified position of the table and stopped by a stopper so that only one part will be processed and the next one will be allowed to be processed after the table has been rotated to next position.

5. TROUBLESHOOTING 5.1 Function Chart

The function chart was drawn for two times to get a clear understanding figure. To program two modes with two different flows, the programming flowchart was confused for many times until the final function chart has been done.

5.2 Ladder Diagram

Since the conventional interlocking has been used, the latch was of different input or entirely missing for many times. The ladder diagram was separated into two parts, accepting the part and rejecting it.

Two Power-On-Initialization flags are used because the diagram is the combination of two processes. Although the ladder diagrams are drawn separately and later combined, there are some problems about the symbols. The reason is that the same symbols are being used to command same output for different processes. After changing those symbols into different ones, the problem is fixed.

The last thing to fix was the timing. Since there is no sensor to detect whether a part is on the lift or not, the cycle keeps extending and retracting continuously. Since all parts are sensitive to capacitive, a capacitive sensor is used to detect. Until then, no steps will be working. After putting the sensor, a timer is added simultaneously so that the sensors have time to detect the proper color and material to decide whether it should reject or accept.5.3 Sensors

At first, the lift-up sensor was misunderstood as lift-down sensor and vice-versa. So, when the program was run, the lift didnt move a single inch. After realizing it, that error was eliminated.

5.4 FreezeWhile Freeze function is being tested, the problem was that after the STOP button is pressed, it stops the whole process and not working when START is pressed since the connections of the steps were distracted. The problem was solved by adding the freeze function at the output of every output step.6. Recommendations1. When ladder diagrams are drawn separately and combined after that, there is a problem that same input symbols of same condition may output a same output with different commands which means the program will not work for both diagrams at all.

2. When a freeze function is added, the function should not be included in the sequential steps. Its a good idea to put that to output of those steps.

3. Before start working on any programs with PLC, everyone should check the sensors and their input bit numbers carefully.

7. ConclusionsMini-Project is a composition of 5 different stations, together forming the COMMSSIONING FESTO MODULAR PRODUCTION SYSTEM (MPS-PLUS). Every station is similar in a way that they are all planned in function chart and programmed in OMRON CS1G PLC and transferring datas to the PLC-controlled machines.Using a properly programmed ladder diagram, those stations can be programmed in various working fields.

8. Appendix A-Final Printed Ladder Diagram

9. PLC MINI-PROJECT WEEKLY LOGBOOK

Week 1

Started working by studying the sequences of the whole process. The function chart for both auto and manual mode was completed within a day. Before the ladder diagram was finished, require timers, steps, lamps, sensors and lifts were listed down as mentioned in the lab sheet.

Week 2

The ladder diagram was drawn for the first time. Accepting and rejecting the material pieces were completed. The timer to control the amount of time to read the color and material was set. The process works very well in both auto and manual mode. Freeze method was started trying on the same day, but didnt work due to programming problem henceforth it was postponed to next week.

Week 3

In accepting the right color and material, the following steps were continued to advance. At first, the steps were not working as they were planned because of misunderstanding about the lift-up and lift-down sensors. After fixing that error, the steps for accepting the material, moving it up, extending the cylinder, retracting the cylinder and moving down works smoothly. Even though, the freeze function was still not functioning well. On week 3, the manual and auto modes for both accepting and rejecting parts were successfully programmed to work perfectly.

Week 4

The function chart had been redrawn with more understandable format. The freeze function was also finally working using STOP button and an extra step which is named freeze. The problem that the sensors had very short time to read the color and material was also fixed. Even though the function chart was redrawn, there were not many changes in the ladder diagram.

Therefore, the testing station was programmed successfully to distinguish the color and material and decide which piece to be accepted or rejected.