PLC questions

My son works at a place where the different types coatings are applied to drills, mills and other types of machine cutting tools to make them last longer. I observed him one day starting a new batch of tools to be coated. The machine he uses has an HMI screen. This machine uses Siemens controls. The HMI screen ask him about ten questions about the batch he was about to start. Type of coating, targets, are just some of the questions he answered on the screen. When he was done, a message came up on the screen and ask him if was sure of the selections he had entered were correct. He clicked “yes”. A message appeared on the screen “downloading to PLC”.

My questions are, will an Allen-Bradley PLC perform the same type of operation?

Is this a type of recipe?

Are the different variables my son chose from stored in the HMI device?

Is the HMI really downloading a new program into the PLC, or just changing values in registers?



Thanks,

Herb

weilerot said:

will an Allen-Bradley PLC perform the same type of operation?

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Yes, this is a standard and frequently implementd task on many PLC brands.

Is this a type of recipe?

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Yes.

Are the different variables my son chose from stored in the HMI device?

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It certainly appears so, although they may be stored in the PLC memory as well - as long as there is enough memory for that.

Is the HMI really downloading a new program into the PLC, or just changing values in registers?

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Just changing the register values, i.e. the data. PLC programs (the code) may be modified only by means of a proprietary programming software, in most cases specific to a particular PLC brand and family.

Herb,

What you are witnessing is someones efforts in creating a machine utilizing a PLC as the brains and the touch screen as the user interface.

The touch screens we utilize offer what is known as recipe capabilities, whereby different parameters are stored in the touch screen and upon selection by the operator, downloaded to the PLC.

What is stored in the touch screen will depend on how it was programmed. There may be specific selections or a range that you can choose from. For example, a timing set up, will likely offer a time range to select from.

The touch screen is not actually downloading a new program to the PLC, but rather downloading new variable information that the machine designer set up. You will likely only be able to select between predefined ranges set up by the programmer.

Any PLC will work in conjunction with a touch screen, so long as there is a communications driver for that PLC. For instance, we have a ModBus driver...therefore any screen we use will have to communicate with our PLC via ModBus. The same would go for Allen Bradley. There is really no concern on this, in that just about every display manufacturer offers the many communications drivers for their products.

So, in answer to your question, yes an Allen Bradley controller will work...but the key will be in the programming of it and the touch screen associated with it, to obtain the desired results.

The questions, and confirmations are the efforts of the developer of the machine.

Hope this gives you some additional information.

God Bless,

“downloading to PLC” could be construed to mean "downloading a program to the PLC", but when you understand how these things work, you will see that it really means "downloading the data (just entered on the screen) to the PLC".

Parameter data can certainly be used by the PLC to create a recipe or a programmed list of instructions.