f kk

I'm new to siemens so this question knda stupid

Why I cannot point HI_LIM/ LO_LIM to a tag I create already (it only accept number), even in OUT, I cannot point OUT to my tag

f kk

Thanks to point out ! It waas a stupid question

Another question is ! the first rung in your FC108

Raw reading from an analog device (4-20ma) is from 0 to 27648: how do u calculate this number ??? and is it fix for all of the device as long as it 4-20mA device or it may change depend on device ???

alany

I am testing the scale function with STEP 7 Professional V11 SP2 (TIA Portal).

When I assign input 50 with low Limit 0 and high limit 100 scale range, the ouptut gives unreasonable value as real number as simulator shows.

Please see attached
would you please help to explain?

Thanks

Alan

SCALE: Scale

Description

The "Scale" instruction converts the integer at the IN parameter into a floating-point number, which can be scaled in physical units between a low limit value and a high limit. You use the LO_LIM and HI_LIM parameters to specify the low limit and high limit of the value range to which the input value is scaled. The result of the instruction is output on the OUT parameter.

The "Scale" instruction works with the following equation:

OUT = [((FLOAT (IN) – K1)/(K2–K1)) ∗ (HI_LIM–LO_LIM)] + LO_LIM

The values of the constants "K1" and "K2" are determined by the signal state on the BIPOLAR parameter. The following signal states are possible on the BIPOLAR parameter:

• Signal state "1": It is assumed that the value at the IN parameter is bipolar and in a value range between -27 648 and 27 648. In this case the constant "K1" has the value "-27 648.0" and the constant "K2" the value "+27 648.0".
• Signal state "0": It is assumed that the value at the IN parameter is unipolar and in a value range between 0 and 27648. In this case the constant "K1" has the value "0,0" and the constant "K2" the value "+27 648.0".

When the value at the IN parameter is greater than the value of the constant "K2", the result of the instruction is set to the value of the high limit (HI_LIM) and an error is output.

When the value at the IN parameter is less than the value of the constant "K1", the result of the instruction is set to the value of the low limit value (LO_LIM) and an error is output.

When the indicated low limit value is greater than the high limit value (LO_LIM > HI_LIM), the result is scaled in reverse proportion to the input value.