I’m creating this thread for newbies to share and struggle together! All welcome, but be prepared for very basic issues, etc.
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I have a question about using a Loop Point (PID). I have a problem that I’m working controlling two boolean writable controled boilers. I’m following an example I found in a book. There is a numeric writable setpoint and temperature as inputs to the loop point PID. It drives the boilers through a “sequence linear”. My questions is this: How can a PID loop control boolean points? Maybe the sequencer does something I’m not clear about, but isn’t the whole point of a PID loop to use it’s algorythm to change the value at different rates depending on how big the difference is between the temp and the setpoint? It seems to me a boolean is either on or off.
Would love to hear someones input on this.
This is the books diagram I’m following.
So effectively the sequence linear takes a numeric input such a loop and will divide it amongst the stages you have set up. Once it reaches one threshold, it’ll turn on a stage, and turn on another once another threshold is reached.
Personally I don’t use these blocks at all. I will make a hysteresis’ block(s) to generate my stages.
In bed now but when I get a break in my N4 Class I’ll go into more detail.
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People use the sequence block to take a cooling or heating loop and start a series of boilers or compressors (DX Cooling). You don’t see this approach for chillers as there are many more things to consider for chillers.
To my knowledge, you cannot manipulate the numbers in which things turn on and off, which is why I prefer to use a hysteretic approach to controlling them, that and with time delays to ensure I don’t short cycle my equipment.
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This makes sense. I really appreciate the answers. Like you say, I think setting up hysterisis makes more sense.
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First, this is in no way time sensitive. I’m trying to learn to go back to a previous version of a .bog file that I have saved as a backup. I know exactly where it is, and I usually just copy the backup and paste it into the config folder of my running station. Problem, I think is, I configured a .bog protection passphrase and it’s not allowing me to do this. I’m wondering what the easiest way to do this. I’ve looked in the help docs at the “Editing the .bog file passphrase offline” but this requires .bog file to be a zip file. Do I really have to go this route? It seems like it should be a bit easier to go back to a backup file on the same platform. The .bog protection icon is grey and not active.
To edit the bog file protection, open the bog file and click on a component. Then to go File Bog File Protection
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Charles, thank you as always for your answers! This sounds more like what I was expecting but not finding! I will try this tomorrow and report back!
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Well, that would have been the solution if the problem I had was the problem I wrote about! I think I was actually trying to copy the back up .dist back up file as a .bog file. I did a little more digging, and found that I probably could have used the Distribution File Installer like on a youtube video I watched, but because I’m connected to a pc platform instead of controller platform, that isn’t open to me. This is starting to feel like when I self diagnose myself instead of seeing a doctor!!
So I’ll just ask: How would I revert to a backup that I saved using the option of Right Clicking my station, and using the “Backup Station” drop down menu? And this is just on a PC, and not connected to a controller platform. The backups seem to be saved as .dist files, not .bog files.
Thank you for your patience!
Oh. Go ahead and right click on the dist file outside of workbench and unzip it. You could also rename .zip. Then in there, you can go in and find the station
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This! was the answer! Thanks again Charles. I thank you for reaching down the ladder to a newbie! You guys have been so helpful! Hard to overstate how much! Cheers Sir!
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So I also take a similar approach to Charles in terms of using a hysteresis type approach.
Although this bit of logic uses a couple of custom components, they could be replicated quite easy using the standard kitControl blocks.
The 2 RescaleTo modules just take the loop output and scale it to 0-100% based on the input being between the values set in InA and InB. This means we could divide the loop output up into any number of required stages by adding the correct number of rescale modules and setting the levels accordingly. 3 stages for example would be 0-33, 33-66 and 66-100.
The Hysteresis Limits modules are a modification of the normal TStat module, But instead of having a Setpoint and Difference, we have 2 fixed levels at which point the output switches On and Off at. In this example the output comes on at 10% and off at 2% (which is effectively 5% and 1% loop output based on 2 equal stages).
I’m sharing this so you can see that the joys of programming mean there are just so many ways to achieve the same result.
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I agree with your direction. My brain was balking about attaching a PID loop to binary outputs!! I now see how that Sequence Linear “converts” it into a format that the Boolean-Writables can use, but my brain still doesn’t like it.
Hello everyone. New to the Niagara platform. Trying to understand at what point do you transition from a graphics package like WebCTRL to Niagara?
-For Context-
We build clean rooms and dry rooms for pharmaceuticals, aerospace, and small custom compounding facilities. I don’t have a mentor to discuss this with so here I am.
Appreciate the feedback.
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