VLT_FC302 via profibus to S7

Nepiter

Member
Join Date
Apr 2010
Location
At job
Posts
79
I have connected Danfoss FC302 vlt to profibus, and I'm controlling that with S7300. Ppo type is 6.

I am able to start and conroll vlt.
But when I try to read reference[unit] from vlt, something goes wrong.

Example:
I will set speed to 5hz.
VLT shows at the panel: 4,999hz.
I will get 4999 to db1.dbw0 (value moved from pew292 which i have choosed to receive reference[unit])
Everything is ok, until i jump over value of 32hz..
32Hz gives me value of 32001. That I can handle..

But, when I set speed to 33hz, value jumps to -32534 at db1.dbw0..
34Hz gives -31533, and so on..

How could I convert this value to show same value as I have set..?

(If I move pew292 to db1.dbd2 (double word) I can reach value of 64, and after that, value jumps again to minus value..)

o_O
 
Word = 16 bits = 16 bit integer = range from 32,768 to -32,767.

Either set PEW to PED, or change the scaling in the FC302.
 
..That was exactly what I was thinking..
But, I could not understand that I need to reserve two words from VLT, to send reference to PLC...
I just thought that if I reserve 1 word for "reference[unit]" VLT will send everything what fits in to that word. And if I choose 2 "reference[unit]", I will receive twice same information in two words.

But it was not like I thought..
Now I have reserved 2 words for "reference[unit]" at vlt, and I am reading PED, from at CPU.

Yes, now it works nicely!!

Thank You!! :D:D
 

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