Practice Programming Tip for Beginners

[KalleOlsen]

Yes you're right, Lancie.

I think it would have been nice to have some already prepared pages with solutions for the most common questions. Now we have to dig up the same examples, or to rely on Mr. Alzheimer to find old threads with the relevant contents, iteratively.

Examples of 'prepared pages' could be
- The never ending flip-flop story
- A simple sequencer
- The Temp variables trap in Step7
- Profibus trouble
- ....

Kalle

 

[Lancie1]

Kalle,
There are a lot of solution-type programs posted in the PLCs.net Downloads section. The problem is, as for most sites, there is a bunch of trash in with the good stuff, and you have to know enough to recognize the diamonds in among the lumps of coal. Most students can't do that, so we go on, and on.

 

[fhervrylesestoso]

Maybe this kind? http://www.plctalk.net/qanda/showthread.php?t=64569


I agree "student problems are always urgent"
I disagree "plese help me its urjent"

+10000 with this one.

"ask help politely"

 

[vikas1947]

thanks

thank you for helping me sir they were awsam task and i will not forget your help sir will you provide me some task containning timer and counter and other logics

 

[vikas1947]

thanks

thank you for helping me sir they were awsam task and i will not forget your help sir will you provide me some task containning timer and counter and other logics

 

[Lancie1]

Okay, here is one about two former PLC students that flunked out and had to go to work in a chicken-processing plant.

The situation: You and your friend Joe flunk out of the PLC training class. Deciding to go into the job market, the best jobs you can find are at a Chicken Processing Plant. Your jobs are to take incoming chicken carcasses and hang then on the overhead chain conveyor that takes them into the scald-and-dip tank.

The boss finds out that you and Joe have PLC training, so he asks Joe to make some changes to the Chicken Conveyor program to make it run faster. Joe says that there is no reason to tell him that you had flunked out of PLC school.

One Monday after a wild weekend party, Joe is hanging a chicken on the hooks. He slips on the wet floor, and the next hook catches Joe's belt and drags him off his feet and towards the scald tank. Your job is to stop the conveyor before Joe is scalded like a dead chicken. Unfortunately, the program Stop Pushbutton does not work exactly as you and Joe thought it would....

Save the LogixPro Chicken Conveyor simulator program on your hard drive, then load it, and click "Simulations, I/O Simulator" to display the Input Switches, then download the program , and switch to run mode. The Chicken Conveyor (O:2/0 will start running immediately). Then you have 3 minutes to stop the conveyor before Joe is scalded. Remember, these guys are not very good PLC programmers! To try again, reload the program from your hard drive.

 

[vikas1947]

Vikas, Here is a classic problem from PLCs.net to help you enhance your programming concepts.

PLC Logic Project One

1. When light one (input X0) is on, YO is True.
2. When lights 3 and 1 are on Y2 will be on.
3. When all 3 lights are on Y3 will be on.
4. When lights 1 and 2 are turned on, Y1 will be on, and remain on even after either light 1 or 2 is turned off. The only way to turn Y1 off (after it is on) is to turn light 3 on. If Light 3 is on and light 1 and 2 are all on, then Y1 will be on.
5. If no lights are on Y5 will be on.
6. Y4 will be on only if one or more lights are on.
7. Add an additional switch to your program so that when X3 is true, the above program will work in reverse (as described below in Part 2, Steps 1 through 7).

Part 2: Program will work in “reverse” as follows:

1. When light 1 is on Y0 is now False.
2. When light 3 and 1 are on Y2 will be off.
3. When all three lights are on Y3 will be off.
4. When lights 1 and 2 are turned on, Y1 will be off (and remain off until light 3 is turned on). Y1 will remain on after light 3 is turned off (as long as lights 1 and 2 are both on).
5. If no lights are on Y5 will be off.
6. Y4 will be off if 2 or more lights are on.
7. If you add an extra input to the circuit (say X4), could you make all the outputs flash when X4 was true?

sir i am very thankfull of you i would like to do some more task on additional instructiuon like timer counter

 

[Lancie1]

I suppose that you did not like the Chicken Conveyor, which uses Timers? Here is classic Timer problem.

Design a PLC program and prepare an I/O connection diagram and ladder logic program that will run the relay logic circuit shown in Figure 1.

Figure 1              START PB2

L1          STOP PB1  __|__                 OL   L2

|       o---o_|_o---+--o o----+--+---(M1)---|/|---|

|        HAND       |  M1-1   |  |                |

|                   +---| |---+  |---(TDR1)-------|

|----o-->                        |                |

|         AUTO      PS1          |                |

|       o----------o / o---------+

|       |            O           |

|       |   TDR1-1      TDR1-2   |

|       |----o / o--------| |----|

               ^

            (30 sec.)

 

[Lancie1]

Here is another Timer problem. You could use counters in place of one or more of the timers.

Given the following I/O list, using two timers, design a PLC program that will cycle the Outputs ON for 2.5 seconds, then OFF 2.5 seconds.

I/O List
Flashing Light L1 (flashes about every 0.2 seconds)
Selector Switch S1, maintained contact, normally open

 

[Lancie1]

Correction: Previous version left out Light L2.

Given the following I/O list, using two timers and other available PLC functions, design a PLC program that will cycle the Outputs ON for 2.5 seconds, then OFF 2.5 seconds.

I/O List
Flashing Light L1 (flashes about every 0.2 seconds)
Flashing Light L2 (flashes about every 0.2 seconds)
Selector Switch S1, maintained contact, normally open

 

[vmadankumar]

HAI FRNDS., I AM MADAN NEW MEMBR, PLZ TRI TIS PROBLM,

Switch1 is ON -------- Lamp1 will b ON Lamp 2 is OFF
Switch1 is OFF -------- Lamp1 OFF,Lamp2 will b ON

just try it., but using following conditions.,

1. dont use advanced commands (shifting commands or move., etc.,)
2. dont use set & reset conditions
3. only use normal NO & NC contacts & Normal O/P ins.
4. dont use Lamp1 "HOLDING" Contacts 4 Lamp1 tis is main condition
5. otherwise use L1 holding contact 4 Lamp2.

any 1 solve tis problm plz update the mail.

 

[vmadankumar]

plz clr my doubt i just learned the GE-FANUC plc. how to use the analog i/p plz give such expls., and exple ladder program.., plz i wait 4 ur ans.,

 

[Lancie1]

switch1 is on -------- lamp1 will be on, lamp 2 is off
switch1 is off -------- lamp1 off, lamp2 will be on

 

|    s1       lamp 1 |

|---| |-------(l1)---|

|                    |

|    l1       lamp 2 |

|---|/|-------(l2)---|

 

[vikas1947]

thanks

i was never thought that i will get hlep this much thankyu aall for helping me

if anybody have some more practice task with advance instruction so please post me

 

[vmadankumar]

hello mr/ms/mrs., lancie1 ur ans is more are then equal but at the time of starting lamp 2 is always on. but i want initially all o/p's r off condition. here L2 is ON at starting. this problem is depend on the PLC PROCESSOR scanning. just try 1's again. i send ans 2morow.,