Better documentation of memory bits

Hi DataTree,

thank you for your suggestion. 
You can make such a recommendation in the feedback-area at the bottom of the documentation side.

Best regards,

Jen_Moderator

@Jen_Moderator:
What you suggest is only helpful if DataTree known which document is not good enough. Then he has a starting point to make his suggestion.

@DataTree:
From my point of view the documentations are enough. If you have read through these are also open for debate.

It is somewhat like the situation of a seeing man trying to explain to the born blind man how the colour blue looks like. We stand at different levels of experience.

If you have an example of some knowledge you have discovered that highlights the fact that the Siemens documentation does not speak well enough for a self-studying learner, please tell us. As much as we try to convey concepts to you, you can help us by understanding better what your situation is.

Let us refer to the manual of the S7-1200 which I linked to for one of your questions. What is the sections I highlighted did not meet with your expectations?

If we have a better understanding of your position, then we are better equipped to direct the efforts of Siemens in documentation. I do urge you though to get in touch with someone who knows some concepts as to instruct you one-to-one. This remains the best way. Learning a new skill is not easy - there is no shame in fighting the struggle.

With sincere encouragement: Best of luck with your journey.

I see it similar to #dP, with most of the statements I agree.

The basic (what is a bit, what is byte, what is a word) must already know and master.

In my opinion, there will be no operating instructions for a well-known PLC, which begins with "Adam and Eve" of PLC programming.
That can not be the meaning of a manual (my opinion).

Here is are simple examples of things I can not find in any documentation:

In the HMI events for buttons 2 of the options are press and release. If I set a button on the HMI to setbit when the button is pressed, does that mean the memory bit goes back to false the instant I am no longer pushing the button ? Or does it stay true ? Or does it change in the next PLC scan ? Or does it change in the next network ? Or does it change the next time that memory bit is used ?

Can I set the HMI button to setbit while pressed and then reset the bit when released ?

Can I set and rest more then then one memory bit at a time with each HMI button ? The portal lets you do it but I can't figure out if it is actually working or not.

Can I use a memory bit in more then one network ? Or does the memory bit get erased when each network ends ?

Can you set a memory bit to more then one coil ?

Does a memory bit get erased every time the PLC starts a new scan ?

@ ixo65  No offense at all taken. I realize the questions I'm asking are super basic. So basic that Siemens doesn't even bother to put them in the documentation. That is why I'm asking for help in forums. I don't know where else to get the information. I probably have 30 hours of programming and testing over the last 2 weeks doing experiments just trying to figure out how these memory bits work.

I feel like a monkey just blindly banging on an engine with a wrench and sometimes I get lucky and hit something and it works. Believe it or not but I actually have a bachelors degree in computer information systems. They never really went into much technical stuff, which I always wanted more of. So I left there with a mountain of debt but no real skills. I could write a book about how frustrated and angry I am with my whole university experience but I will cut it off now so you people don't take me for a raving lunatic. I just wanted to put a short bit about it so you understand a bit of my background hoping that that will help the communication a bit.

In university, I wrote a few programs in C and that made sense to me. Declaring an int or char variable in a C program and using it makes sense. These memory bits in Siemens PLCs do not seem to behave with any consistency. So my experiments seem to be mostly fruitless. There is a piece of the puzzle that I just can't see. I feel like if I could get the basics I could teach myself more. 

Thank you to everyone who has replied to me. 

DataTree

[snip]
a bachelors degree in computer information systems
[snip]

The certificate you receive as proof of getting such a degree is but the "permission slip" for further self-driven learning on how the world actually works.

You will have to see what you can extract from the demo I gave you in your other topic. Follow that up with specific questions. We will be more of help to you then.

#dP

 

DataTree

[snip]
a bachelors degree in computer information systems
[snip]

The certificate you receive as proof of getting such a degree is but the "permission slip" for further self-driven learning on how the world actually works.

You will have to see what you can extract from the demo I gave you in your other topic. Follow that up with specific questions. We will be more of help to you then.

 The demo you put in the other thread was exactly what I needed. Thank you.