s7-300 analog output

amrhk · Jan 16, 2018

hi
i am using s7-300(CPU 313c). when i try to use FC106 unscale function, i can change IN manually but there is no effect on OUT.
i wrote PQW752 in OUT for analog output.

cardosocea · Jan 16, 2018

I think your problem is really the SCALE function.
The value being written to MD2 on your network 2 should be between 0 and 300.

Is MD2 used elsewhere? Or forced perhaps? Remember that when forcing Real values with a Siemens PLC you need to type the .0 at the end of the number.

boneless · Jan 16, 2018

Welcome to the forum!

I think your input values are fine, however, your are writing a status word (2 bytes) to MW1 and then a real to MD2. Second network, your status is MW2. These overlap.

If you use MD4 (assuming it is available) it should work.

Rule of thumb, use even numbers for W and D values.

cardosocea · Jan 16, 2018

Well spotted boneless.

amrhk · Jan 17, 2018

boneless said:
Welcome to the forum!

I think your input values are fine, however, your are writing a status word (2 bytes) to MW1 and then a real to MD2. Second network, your status is MW2. These overlap.

If you use MD4 (assuming it is available) it should work.

Rule of thumb, use even numbers for W and D values.

Thank you.
I changed the address's and it works properly. But still I can't view the value of PQW752 in the block, I can mesuer the output voltage with multimeter after running PLC.

s7-300 analog output

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