S7-Graph newbie questions

Hi,

I've just started trying to use S7-Graph and finding some of the features a little confusing.

For example, each step can be configured with an interlock that has to be satisfied before the actions in the step can proceed. What's the difference between that and the logic of the transition prior to the step?

e.g.

Let's say that T1 has I0.0 in it, so S2 can't become active until I0.0 is TRUE. Suppose you wanted the actions of S2 only to happen when I0.1 was TRUE, what's the difference between putting I0.1 in the interlock, and putting I0.1 in series with I0.0 in T1?

I'm sure that there'll be more similar (and possibly silly) questions over the next few days.... I've looked at both S7-Graph guides and searched Siemens site and also this forum. The general consensus seems to be "trial and error till you figure it out yourself".

Thanks,
Martin

Hi Martin,

I haven't used S7-Graph for a while (and never that much) but, if I remember correctly, you can specify a timeout for the interlock so that an error can be reported. I'm sure others will come up with better answers.

I was at Shotton Paper a few weeks ago - they seemed to know nothing about your Polish adventure.

Nick

Hi Martin,

I found this in the help, which is a little more helpful than my previous post.

Nick

MartinW said:

Hi,
The general consensus seems to be "trial and error till you figure it out yourself".

Click to expand...

Have Siemens stopped offering training courses for S7-Graph ?

hii frnds..

i'm very new to Siemens S7..
Please provide me with the FBD with the conditions specified below..I'm planning to do the programming in Siemens S7 PLC..
The conditions are as follows...


INPUT (Let it be "A")--- 4-20ma..
this comes from a potentiometer..so the voltage signal from the pot is converted into 4-20ma signal..
OUTPUT(Let it be Y1-Y10)--- 4-20ma
output is the input itself..(ie. A=Y1,Y2 etc..)
there should be 10 outputs each of 4-20ma..
so the single output should be multiplied into 10 outputs..
Also we should be able to adjust the Gain and Bias(Increment or Decrement) of each output individually...This is done using Push Buttons respectively...
At each incremental press in the corresponding push button there should be an increment of 10% of the output from that particular output (Any from Y1-Y10) which is the operators discretion..
Similarly,at each decremental press in the corresponding push button there should be a decrement of 10% of the output from that particular output (Any from Y1-Y10) which is the operators discretion..

These are my conditions..Please help me..

With Regards...
Arjun S Nair

L D[AR2 said:

Have Siemens stopped offering training courses for S7-Graph ?

Click to expand...

Hi Simon,

No there's still a course. In fact Siemens are running one in Manchester on 20/21 July. I tried to get on it but couldn't. I meant the consensus on here. Siemens help documentation can be a bit opaque at times.

I know Graph was used on the CT610 machines, did you write any of that?

Cheers,


Martin

Manglemender said:

Hi Martin,

I found this in the help, which is a little more helpful than my previous post.

Nick

Click to expand...

Ah, so whereas the Transition, and therefore progression to the next step executes all the actions in that step, the interlock can be used to selectively execute actions within a step, e.g. where you might have say, 5 actions in a step, you could program 3 of them to only execute when the conditions of the interlock are ok, whereas the other 2 would execute regardless of the status of the interlock?

IF that's the case, then that seems like a good way to complicate an otherwise simple sequence? Why wouldn't you break those down into separate steps?

As a general question to those who use Graph a lot, what are the most helpful philosophies to live by when programming sequences in Graph, especially those not contained in the manual!!!

There's a basic self study course on their SITRAIN website you might want to have a look at?
http://www.sea.siemens.com/us//training/Self_Study_Courses/Pages/blended.aspx?rc=1

Another question - is it better to make the sequence "all containing", i.e. turn outputs on/off from within the sequence, or use the step number in another block which can OR the automatic functioning with manual controls?

The Siemens manual for Graph seems to imply that when there is manual and automatic control of a piece of equipment, you should separate them. I'm not sure if this is a good idea or not...

I prefer 'homemade' sequencers with stepcounters, but I allways manipulate the outputs outside the sequencer. The reason is that I can include interlocks that are allways active.

Kalle

pls help me..

any one pls reply to my question??

Arjunnair88,

You will probably get more replies if you ask your question in a new thread, rather than adding unrelated questions to someone else's thread.

Regards,
Martin

oh k thnx martin..i'l post a new thread..

Regards,
Arjun