I need some help on writing ladder logic for EZIO-4THIE to record thermocouple temperature. I am new to PLC programming.

Hi sala. Welcome to the forums!

Perhaps we need to start with a little more detail on what your application is. We'll be glad to help!

Regards,

Application is to detect any bad/broken thermocouple connected to the all the 4 channels. Thanks

Here's a copy of the documentation, if you don't have it.

When you configure the module you can set the type of notification for broken TC.

"Low Value": the value in the IR register will be -32768 (decimal)
"High Value": the value in the IR register will be 32767 (decimal)

Thanks but my question was regarding the ladder logic corresponding to this. I am not sure how to write the ladder logic.

I also added the file so you can play with it.

Thanks Jordon

If you want to dig in a little deeper on PLC Programming, I recommend a couple of resources:

http://www.plcs.net/: Excellent tutorials and an online PLC simulator.
The sim is ok, but can be a bit flaky at times.

Therefore, I also recommend http://thelearningpit.com/. Simulates a SLC 500 series, (sorry, EZ guys) with applications that you can program. I use it to train my guys here at work. Once you get the hang of ladder laogic, you can apply the theory to any platform.

Ladder logic is ladder logic is ladder logic. The differences are in the format of the functions.

Good luck!

Regards,

Hi Jordon,

How to use the CJC sensor on this module? Do I need to write a ladder logic to use this?

Thanks,
Sala

Basically I need to detect reverse polarity of the thermocouple.

What is Warm up time?

It's automatic, defaulting to the internal one. If you use an external one (the documentation recommends an LM19), then it's also automatic, but you lose one input, since the LM19 will use Input 4


A reverse hookup should give a reading that is well outside the boudaries of the process. While I'd be willing to bet that it will give a similar reading to an open T/C, your best bet would be to hook one up and see what reading you get. Adjust your alarm accoringly.


When the ambient temperature changes, most T/C measuring instruments may drift by a few degrees. Typical T/C-input instruments take from several minutes to a half-hour to stabilize to within a couple of degrees.

Hope this helps.

Regards,

Hi Jordon,

How do I introduce a limit for the output supposedly I want to display the thermocouple is fine only if the temp range is between 20-30 degrees Celsius?

Also, I have a peculiar problem:
Right now I am using two EZIO-4THIE modules and using only 3 channels in each ( not using IR4 and IR8), but when I display the output of all 6 channels at once the readings goes on decreasing from IR1 to IR8 like if IR1 is 32, IR7 will be around 22, the difference being around 10 degrees. How to resolve this issue?

Thanks for any help,
sala

Well, to the module, you can't. But in the PLC logic, you can use the Limit Function:







There's probably medicine for that. -- Sorry, sala, I've been working way too many hours, and I'm in an odd mood.




I'll be honest, I haven't seen anything like this. The only thing I can recommend at the moment is to swap some of the T/C inputs around (i.e. IR1 and IR2), just to make sure there isn't a zone issue.