S5 to S7 conversion Analog output scaling

[rgraut]

Hello Experts,

I am working on S5 to S7 conversion project on which stucked on analog output scaling.

In S5 following logic is written for analog output coming from S5-PID(OB251).Two analog outputs are used for Course and Fine action.

L DW 48 // PID output ranging from -17980 to +17980

L 2#1111

AW

SLW 4

T QW112

L DW 48

L 2#1111111111110000

AW

T QW114



My question is how to convert this in S7. How do i scale analog outputs in S7.



Thanks

 

[Diameter157]

Simatic step 7 for S7-300 series or Tia portal for 1200 series?

If I recall correctly you use FB-41 for old step7 and use norm_X and scale_X for the s7-1200 in tia portal.

 

[rgraut]

It is Simatic S7300

 

[rgraut]

Thanks for the reply it Simatic S7-300 and i have converted OB251 with FB41 but i do not understand the scaling done to Analog output.Please guide me to understand how the scaling of analog output is done.
and How to implement the scaling in Simatic S7-300

 

[sigmadelta]

The S7 Analog Output is a value from -27648 to +27648

For Example, if you have a 4-20mA output signal:

0 value in the PLC will produce 4mA
27648 in the PLC will produce 20mA

If you have +/- 10V output signal:

-27648 in the PLC will produce -10V
0 in the PLC will produce 0V
27648 will produce 10V

Which S5 PLC model are you using, and what is the part number of analog output module? The Analog output value in the S5-100U PLC is +/- 1024 shifted to the left 4 bits.

 

[Diameter157]

I was wrong, FB41 is for PID and FC105 is for scaling.
You may want to replace the whole PID with a new FB41. Just drag the block into a new network, select it and press F1.