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How to Scale a analog value?

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hello guys....How are you all?:-)

im new to siemens plc, so i dont know how to scale analog value in STEP7 plc's?

and also i dont know how to use AI,AO,DI,DO? how to address them?

can anyone help me? 

Edited by gnana31

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You will find the addresses for the inputs and outputs in the hardware configuration.

Siemens use octal addressing for inputs, outputs and internal memories.

A digital input is for example addressed I5.3, bit 3 of input byte 5. They normally starts at I0.0 at the first input, but you can change this in the HW configuration.

The same is for the digital outputs, but instead of using an "I" as prefix, they are written by using a "Q" (Q0.0-Q0.7 and so on).

Analog inputs and outputs are actually input words and output words, they are addressed IW and QW and occupies two bytes.

If your first analog input is addressed IW120, the next is addressed IW122.

Input word starting at address 120 and occupies input byte 120 and 121.


Siemens has a library function for scaling raw values to engineering values, just search the library for the scale function.

Edited by Bryll

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