Need Advice on Automating a Machine.....

I'm looking for a quick advice. To all you guys that have automated a machine, what are the steps that you follow to developed your project?

Do you get electrical schematics and work from them to determine the varies aspects of your project like, I/O, Power requirements, etc.

What is the very first thing you guys do?

The very first thing to do is get a very detailed and exact step by step description from the people requesting the project. That must be followed up with the details reduced to writing and signed off by these same people. That will protect you when changes are made.

A flowchart will help define and visualize the steps for operation. Something like Diagram Designer (one of my favorite freebies) is good for that sort of thing.

If they have good drawings for you to go off of, it should help you decide what I/O, power, etc, is needed.

Keep machine safety in mind, since it'll be your tail feathers in a bind if something happens. Some OEMs will even use a safety PLC and not give the source code until the customer signs off. A rather sad state of affairs in a lawsuit-happy culture.

This machine already exist and its being utilize by the production group. It uses old relay logic all over the place and they want to change it to PLC control.

The drawings are not very good since the machine is like 15 years old and documentation is missing.

do you want the machine to do the same thing as it does now? just using a plc?

Hire a professional to do the automation. Work with them to learn the process if they are willing to let you shadow them.

A flowchart will help define and visualize the steps for operation. Something like Diagram Designer (one of my favorite freebies) is good for that sort of thing.

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I am not a plc programmer yet, but I programmed in c++ and this freebie is a great tool for getting the steps down of a program. If is not a complicated machine I will try and do it myself as long as your employers let you, test for safety and proper operation.

JoseM said:

This machine already exist and its being utilize by the production group. It uses old relay logic all over the place and they want to change it to PLC control.

The drawings are not very good since the machine is like 15 years old and documentation is missing.

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A retrofit like this should be treated as you would a new machine. At the stage where you decide what equipment is needed you can look at what is there to determine what needs to be replaced and what can be reused. You should also take into account the life expectancy of any equipment reused and make sure that these parts are not included in any warranty.

They want the machine to continue doing what is currently doing with the exception of controlling the speed on one particular motor of the process for a more realiable performance.

I want to tackle this project myself. I have the knowledge on PLC and electrical is just that I've never done one full automation.

Jose,
This could be a great learning experience but the tuition will greater than you or your company will expect.
You can plan on downtime, redos, and crashes from out of the blue.
You will hear many negatives here about amateurs but everyone has to start somewhere.
Line up guys to help fix stuff that you are going to break, ask lots of questions and jump in with 2 feet!

WOW. If we all hired a professional, we would never learn how to do it ourselves... Even the professional started somewhere... Just sayin..

I understand completely where you are coming from JoseM.
listen to all the advice, take the tips and advice you think works, and you fill in the rest. If it doesn't apply (c++) just ignore.

I have worked for companies from a maintenance side, as well as OEM's building from scratch. I've done relay to PLC conversions as you are looking at many times as well.

Here is a QUICK summary of my advice (and it repeats some suggestions above, giving credit where due):
1. Gather as much info as you can from the documentation. (inputs, output, motors, etc.) document on an Excel spreadsheet to keep information organized. (Input #, What it is, Voltage, etc.)
2. What you can't find, get from the the machine itself by observation, operation, or just tracing wires.
3. If possible, make an electrical schematic to help understand what is controlling what. For instance, you may have 2-3 relays in series to operate something, and each has a 'interlock' or function. For example, push button #1 (PB1), but the limit switch #5 is not made, which pulls in Relay #5 (CR5), and the signal from PB1 goes through CR5 before it goes to the contactor or whatever. You need good documents to work with before going further.
4. Generate your PLC Hardware requirements (input cards, output cards, etc.) from your Excel worksheet. make sure to add more just in case. (Have 16 inputs? order two 16 input cards, not just one)
5. Start PLC program by entering all your I/O (tags) first. (assigning address of Inputs, Outputs, descriptions, etc.)
6. Here is where the machine flow chart (as mentioned by JordanCClark) will help in creating the ladder logic. Start with the easy stuff, start, stops, etc. Always make sure SAFETY is #1. NEVER let the PLC take care of safety, have an EStop hard wire circuit to stop dangerous moving stuff.
7. Watch out for "loops", like latching a bit, etc. which may start something, and not get it shut off. As a couple people mentioned, if you have a local integrator that you can help out here and there, might help. 1hr. of help can save 2 days of work that you have to re-do....

Good Luck.

If the machine is already being used then go ask the operator's what they want. Of course whether they get what they want is ultimately up to the person who's is paying for the project , but the Operators are the one's that will be using it, what makes their job easier, more efficient ?

a few key points
1. - hire a professional - not always the answer - some of them later ask how to do it on this site......
2. - do a flow chart - while the machine is running - this can be seen
3. - make an I/O list - Include what is on the machine.
4. - Machine Safety - Tackle this carefully - DO NOT USE THE PLC FOR SAFETY CONTROL
5. - use a safety plc - Probably a little too advanced and expensive for you at this stage - no disrespect meant.
6. - add the safety status as an input to the PLC
7. - Consider all PLC outputs as being able to 'Short to a Closed State' - make sure you allow for this when controlling any motive forces.
8. - dont be afraid to search this site for info there is plenty here.

Relay logic - side note.
this makes your current panel look far more complex.
as you are limited to the number of contacts per relay.
so be wary of dual or multiple coils in use.