can someone help me please?

maralop95

Member
Join Date
Aug 2017
Location
mexico
Posts
6
im trying to do this secuence but it dont work :(
jRNbn
 
the first line is a motor, s1 is start for conveyor(line 2), s2 is a proximity sensor that detects an object and stops conveyor(line 3), the lines 5-6-7-8-9 are pistons, s3 its an other proximity sensor(line 4).
it is for a plc siemens s7-300. i hope that you can help me please
 
Welcome to the forum!

You say your sequence doesn't work, so presumably you have made a start on the program? If you can post your code so far, then you should get a few people to offer advice and help you troubleshoot.

You'll have a much harder time if you just wait for someone to post an answer. Most people here will help and guide, but very few will do the whole thing for you.
 
Great! That's a good start.

To help with getting some suggestions:
1. List each of your inputs and outputs and describe what they are
2. Add comments to your ladder logic so we can match the instructions in your code to the inputs and outputs in your list
3. Describe the desired sequence of operation
4. Upload a slightly bigger picture of your logic - it's a little small and hard to read

That will help to ensure we can fully understand and offer accurate suggestions instead of guessing.
 
I don't have the software to open your PLC program, sorry. But a screenshot is fine, it just needs to be a little larger than the one you posted before.

You seem to be getting ahead of yourself and trying to write the program before you have worked out all the details. You must take it a step at a time, or you will end up with a huge mess.

The first thing to do is to use your diagram to write down the required sequence of operation. I'll give you a head start by writing down what I think it should be, you should check it and make sure you agree:
1. Press start
2. Motor runs
3. When Sensor 2 triggered, motor stops and Cylinder A & B extend
4. Once cylinder A & B extended, cylinder C extends and retracts
5. Once cylinder C retracted, cylinder A & B retract
6. Once cylinder A & B retracted, motor runs
7. When Sensor 3 triggered, stop motor and extend and then retract Cylinder D

Once you have your sequence written down, give some thought to how the cylinders operate. Do you have one output to extend each cylinder, and another to retract? Or do you turn a single output on to extend, and off to retract? Do you have sensors to determine when your cylinders have fully extended and retracted? Or are you just assuming that it is extended a certain amount of time after you turn the output on/off?

Once you have worked this out, make a full list of inputs and outputs. For example, your start button will need an input and your motor will need an output. Make a list of inputs, a list of outputs, and assign them an input/output address from your PLC.

Once you've done all of that, then look at your program.

The most reliable way to approach this is to program in a sequence. There are several ways to do this, if you search this forum you will find lots of examples. One idea is to create a integer "StepNumber". At the start, it will be zero. When you press the start button, StepNumber=1. When Sensor 2 is triggered, StepNumber=2. Continue with the sequence in this manner. Then, you just have to determine which step numbers cause the motor to run, which step numbers cause the cylinders to extend, and so on.

Take it one step at a time, document everything you do, and you should be able to work through it without too much trouble. The more documentation you have, the easier it is for you to work on the project, and the easier it is for others to understand and offer advice if you need it.
 
I don't have the software to open your PLC program, sorry. But a screenshot is fine, it just needs to be a little larger than the one you posted before.

You seem to be getting ahead of yourself and trying to write the program before you have worked out all the details. You must take it a step at a time, or you will end up with a huge mess.

The first thing to do is to use your diagram to write down the required sequence of operation. I'll give you a head start by writing down what I think it should be, you should check it and make sure you agree:
1. Press start
2. Motor runs
3. When Sensor 2 triggered, motor stops and Cylinder A & B extend
4. Once cylinder A & B extended, cylinder C extends and retracts
5. Once cylinder C retracted, cylinder A & B retract
6. Once cylinder A & B retracted, motor runs
7. When Sensor 3 triggered, stop motor and extend and then retract Cylinder D

Once you have your sequence written down, give some thought to how the cylinders operate. Do you have one output to extend each cylinder, and another to retract? Or do you turn a single output on to extend, and off to retract? Do you have sensors to determine when your cylinders have fully extended and retracted? Or are you just assuming that it is extended a certain amount of time after you turn the output on/off?

Once you have worked this out, make a full list of inputs and outputs. For example, your start button will need an input and your motor will need an output. Make a list of inputs, a list of outputs, and assign them an input/output address from your PLC.

Once you've done all of that, then look at your program.

The most reliable way to approach this is to program in a sequence. There are several ways to do this, if you search this forum you will find lots of examples. One idea is to create a integer "StepNumber". At the start, it will be zero. When you press the start button, StepNumber=1. When Sensor 2 is triggered, StepNumber=2. Continue with the sequence in this manner. Then, you just have to determine which step numbers cause the motor to run, which step numbers cause the cylinders to extend, and so on.

Take it one step at a time, document everything you do, and you should be able to work through it without too much trouble. The more documentation you have, the easier it is for you to work on the project, and the easier it is for others to understand and offer advice if you need it.


Excellent description, ASF!!!!:)
 

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