Jump to content

Recommended Posts

What type of temperature transmitter and what PLC / I-O module?

If it's a thermocouple, then you'll get a reading that is in degrees to the tenth of a degree and it's a simple matter to do a compare (>=850). If it's a 4-20mA analog input, then you'll need to do a linearization using the specs of the temperature transmitter before doing the compare.

Share this post


Link to post
Share on other sites

This won't work. The V200-18-E1B analog input is 10-bit. Your linearization assumes 14-bit and there is a typo in the X2 value. X1 should be 204, X2 should be 1023 (this is the 4-20mA 10-bit range). Y1 should be the reading on your transmitter at 4mA output and Y2 should be the transmitter reading at 20mA. You are also using an ML for the output from the linearization block. There is no reason for that. The max value will be your max temperature reading (perhaps times 10) and you won't overflow an MI with that.

First of all, you need to configure your hardware for the PLC and I/O module(s). When you do that you will assign an MI to the analog input.

Assuming your transmitter range is 0 to 100 C, then your ladder should look like this:

image.png.7b9459dd57dd8a572122beaa6557fdf3.png

This will turn on the heater when the temperature is less than 80.0 C.

And one more thing, there is no reason to have your compare block in the same ladder rung as the linearization block. Break those up into two rungs like this:

image.png.a75a9fe74d2d80d2579482a5ea1d6e01.png

 

Share this post


Link to post
Share on other sites

Items of note:

- There are no subroutine calls.

- You are still unnecessarily combining too much logic into a single ladder rung.

- Your alarm comparisons should be "</=" or ">/=" instead of just "=", and perhaps should be latched.

- You have multiple instances of comparison blocks with no coil following, so they do nothing.

 

  • Like 1

Share this post


Link to post
Share on other sites

Thanks, for the subroutine, I worked on it but yet to get the function

I get that now, each logic for each rung.

For the alarm, I will latch the output.

For the comparison, I want to use the output of the 3 sensor to open or close a valve and that was why I did it that way but the fact that it is wrong, kindly advice how to go about it.

Also, for the subroutine, is it that each detector will be design In a subroutine or what ?

Please if you have any written program that you know I can learn from, kindly help attach to aid my learning.

Regards

Share this post


Link to post
Share on other sites
57 minutes ago, alagbawale said:

Please if you have any written program that you know I can learn from, kindly help attach to aid my learning.

There are lots of examples that came with your VisiLogic installation. Take a look at them at Help/Examples...

Share this post


Link to post
Share on other sites

I'd like to help, but I don't know what you mean by "cross check". The program has too many problems to discuss coherently in this forum. Do you have a specific question?

Share this post


Link to post
Share on other sites

It's not the purpose of the forum to teach people basic PLC programming.  We're here to help people who have an understanding of PLCs to use Unitronics products.  

If you look through the examples and are still struggling,  I would strongly recommend an online class to walk you through how ladder logic works.  Something like this-

https://www.udemy.com/plc-programming-from-scratch/

I'm sorry to be so gruff, but looking through your code and hardware configuration tells me you're trying to do a rather large system and don't know where to start.

Joe T.

Share this post


Link to post
Share on other sites

Thanks Joe T you are very right, I have the idea but I don't know where and how to start and I go through the examples on the software but not getting the starting point. Please what can be done to this to help my zeal and level?

Share this post


Link to post
Share on other sites
10 hours ago, alagbawale said:

Thanks Joe T you are very right, I have the idea but I don't know where and how to start and I go through the examples on the software but not getting the starting point. Please what can be done to this to help my zeal and level?

So I can only say from my personal experience but I found that going on YouTube and basically watching a ton of videos helped me the most. I started with the bare basics on relays and worked my way from there.

My first bunch of videos were from here... https://www.youtube.com/user/plcprofessor/videos

His earliest videos go very much into detail on the basics of relays and then goes up to programming in RSLogix500, which is obviously not Visilogic but the ideas carry over pretty well. You'll want to start with his Basics01-14 series, and then watch his PLC Lecture series from 01-12. Also take lots of notes because he moves at a pretty rapid pace and you'll definitely want to be looking back every now and then.

After that you should probably head to the Visilogic YouTube page to get the specifics on how everything you just learned applies to Visilogic, namely their playlist on Visilogic Logic and Application. Found here... https://www.youtube.com/user/UnitronicsWebinars/playlists

There are playlists for other more specific things that will definitely help you so I would say go to those for more specific questions. Your biggest tool past the basics however is the help/examples page in your actual Visilogic program, that will go very into detail about how things work and has answers for pretty much any question you can think of that isn't hardware based as long as you take the time to learn it.

Past that it's just a ton of trial and error, and learning from every mistake you make. It helps a lot if you have a goal you're trying to accomplish which it sounds like you do but this step of the process took me a few months of like 6-8 hours a day of studying, so be prepared to put some work in. It may not take that long for a sloppy, bare-minimum type approach but I would say that should not be your goal.

Hope this helps,

-Chris

Share this post


Link to post
Share on other sites
5 hours ago, alagbawale said:

can i run or test my program online without the plc device?

No, there is no offline simulator in Visilogic software.

In order to run your program, you need to be connected to a PLC.

Share this post


Link to post
Share on other sites

How did we go from analog input programming to asking for a sample SCADA system?

@alagbawale- this is how we make our living - programming this sort of thing.  I was under the impression you were open to trying to learn programming on Unitronics.  A SCADA system is quite a high level project.  We do not give away samples.  

Joe T.

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


×
×
  • Create New...