Questions..

[Skywalker 0]

I know this is my first post here.. but I really need some help. I have a test coming up, and I want to make sure that I am doing this correctly. We are using AB PLC's.. so I think this is the correct froum to use. This is really the first class I have taken as far as Programing and what not goes. I skipped a few, and I am regretting it.. On with the questions.. 1. Program a PLC ladder diagram for making a one hour timer using one timer and one counter. The timer should time to one minute and the counter should count to 60 then turn on a light. Label all the components and show the preset values. 2. Program a single cycle control circuit for a cylinder dwell (delay extend) application using one TON timer and a single solenoid valve. Timing occurs when piston is extended and hit the extended limit switch (LS2). 3. Draw a PLC ladder diagram for a ONE SHOT application so that when push button (I:0/4) is pressed output (O:0/0) comes on at once. After a three second delay the output goes off. The circuit may use a TOF timer or uses a latch, an-latch, a TON and any other rungs to make the circuit rung each time the button is pressed. 4. Program a continuous cycle control circuit with a double solenoid valve. The piston will extend when a push-button is pressed. Use a TON timer so that when the piston retracts and hits a limit switch the piston will wait for five seconds then extend. Show a start stop rung to start the cycle operation. 5. Program a AB PLC so that an up counter is incremented by pressing a button on the operator panel of the trainer. A light on the operator panel should turn on each time the button is pressed and stay on for one second. The counter would count to five then turn on a light and lock out the pule button from being pressed again. A reset will be needed for the counter. I know these may be trivial to some, but hey when you are just learning about PLC's and I have only laid eyes on one the minute I walked into the classroom. I had no idea what a PLC was until I took the class and I only took it because they said that it was going to be easy, that was somewhat correct. But I have found a new respect for people that can understand these and really program. I hope to get better in my programing, but I am not really sure about what I program.. will work. I am sure that will get better over time. So if anyone has any advice about these questions I am all ears. The PLC that we use in class is a Micrologix 1500 LSP Series C Thank You for your time and your efforts.

[BobLfoot 302]

Dear Skywalker - Welcome to mrplc and the world on industrial electronics. You are correct this is the correct place to get answers to your questions. But let me be perfectly clear - almost every member here is working for a living and volunteers their time to help their peers and those wanting to join the field. The questions you ask are good ones and we'll be glad to help you work thru them and advise you as you work thru them. The key is you need to make an attempt to answer them first. Post what you think answers some of your questions and any problems or confusion you have about the questions. I doubt anyone here has time to do your homework for you however. Good Luck and welcome aboard, BobLfoot

[kaiser_will 65]

Welcome to the jungle, Skywalker. The tasks you have been handed are excellent first-step PLC logic tasks that many of us still use today. However, time is short and you must be the one to put your first step forward. I highly suggest that you break down your request into separate tasks, post your code idea, ask for input, and go from there. A tip I will pass on that has served me so well in the world of controls programming is to take your task and write it up into a flowchart. I still do this to this day, taking a task and converting into block logic for a flowchart. With a solid flowchart and all my bases covered, I can sit down and crank out a program that will be pretty close to complete right off the bat. Smooth out the simple errors and the job is done. This also helps to get my program sequence in order and not have "spaghetti" logic (a program that jumps around alot for those following along).

[PG Eng 0]

Some good advice in the previous two posts. As stated, have a go at it yourself, post up the code and we'll have a look and keep you on the right tracks. Also, download Hugh Jack's PLC book here http://forums.mrplc.com/index.php?autocom=downloads&showfile=156 if you are having trouble with getting to know the functions of RS Logix. Remember too there is a list of all the instructions with an overview of what they do in RS Logix. If you don't have access to RS Logix outside of where you are learning, visit the Allen Bradley forum here to download a basic version. (RS Logix10 Pt Starter) Good luck!