Profibus in Step 7 with Ladder

[scimdarren]

Hi

I have some basic functions to perform with a Micromaster 420 (PPO3) via a Step 7 program.

I have configured Profibus DP in the HW Config, but after reading the manuals, the method of controlling the VFD in Step7 has still not sunk in.
I would really appreciate some advice or an example of the best practise on 'PZD data handling' in a program.

(Refer to ladder please as my understanding of STL is poor)

Darren

 

[SimonGoldsworthy]

I'm sure there is an example in the downloads section - I haven't done any download myself though.

 

[PLucas]

Darren

This thread might be of some help to you, there is also a link to the file in the download section that Simon referred to.

Paul

 

[scimdarren]

Ok some great leads guys, thanks
It looks as if 'mitar' was in the same predicament as me in that I grasp the PZD concept but cannot implement it.


I think in ladder, not stl. This is what I think I should do:

1) I create a function (FC) for each VFD and its sequence.

2) If I need to control one bit only in controlword1 (eg set ready to run state), I can address it with my own status bits using ladder logic.

3) If I need to increase the frequency I MOVE a constant (my setpoint)to the Control Word2



Am I on the right track?

Darren

 

[dchartier]

Hello scimdarren;

You look on the right track.
Good luckm and tell us how it goes.
Daniel Chartier