m91-2-ua2 Temperature in ladder diagram

[NewToUnitronics]

Hello

I am working with my unitronics m91-2-ua2 PLC.  I have a problem with getting correct temperature from my temperature sensor, type J.

The jumpers in the PLC are moved to  thermocouple input, I am using universal input no. 1.

How do i get feedback in my ladder diagram? Which symbols should I use to get a range fro -40 Celcius to 200Celcius?

[Joe Tauser]

You configure the analog input to a thermocouple type and assign an MI to it.  The temperature will be returned in actual degrees x 10.

Post the PLC program you're working on.

Joe T.

[NewToUnitronics]

I think I got it. Se attached files.

But how can I get a warning if the temperature is under 10 degrees celcius? And a warning if it's over 40 degrees celcius?

[Ausman]

3 hours ago, NewToUnitronics said:

how can I get a warning if the temperature is under 10 degrees celcius? And a warning if it's over 40 degrees celcius?

The real art to programming plcs is to first break down your process to every single procedure you are going to need to achieve your desired result, and then arranging those procedures to achieve this result in the most efficient manner.  (You need to remember that in general plcs are very dumb and need to be told how to do everything.)  I do this using a spreadsheet owing to the ease of moving things around, but there are many other methods including whiteboards, depending on complexity.  (Some people end up with a correctly drawn flow chart once everything is finalised, but for me that isn't needed.)

Once you have done that, if there is a procedure needed that you are unfamiliar with, or haven't used before, you then go to your plc's list of things it can do and find the function/maths/compare etc that best matches what you need to achieve.  You then learn everything you can about the way it works, by consulting the help files, looking at examples and then physically doing a trial, using the plc, of something simple involving that procedure to ensure you are totally familiar with the way it works.  Eventually you can tie it all together into a fully functioning, simple as possible program that the little men, women and gender neutral people (we are very PC on this forum!) running around inside the plc are quite happy to do over and over and over again without getting tired.

In this case it is using different types of compare.

Also, please pay attention to Joe's response. 

On 9/14/2018 at 3:17 AM, Joe Tauser said:

The temperature will be returned in actual degrees x 10.

cheers,

Aus

[Flex727]

Nicely said, @Ausman!

Forum members - this is terrific advice.

[sgull]

Hi

With a thermocouple type input do you need to linearize as shown above?

The attached files above show an input between 0 and 1023 and an output between 0 and 100.

I dont think you can do this with a thermocouple type J.

 

[Ausman]

True Sgull.  You don't need to.  Like I said, Joe's response says it all.  Here is a scrnshot of setting it up.  Choose °C or °F.

cheers,  Aus