Hi all!

I'm new here and have a problem to solve. 

I'm currently programming a 1511F CPU in Tia portal step 7 prof. safety V17 . I need a fixed curve table of 1000 integers in an array. The curve points need to be interpolated to let the service engineer create a predefined fixed curve. I need the 1000 points, because it is going to be transferred to the safety program once the table is created for further processing.

To make life easier for the service engineer, I don't want to let him fill in 1000 numbers but just use let's say 10 or 20 points (100, 200, 300, etc.) to create the curve. Al other points have to be interpolated inbetween (0-100, 101-200, 201-300).

Do you have any suggestions how to set this up (relatively) easy?

Thanks in advance!

Best regards,

Bram

If 20 points are enough, to create by interpolation the other 980, then the latter are useless. 20 points are enough.

However, in similar cases, assuming they are compatible with your request, I write the PLC program so that I can store some real curves from the measurement system, buffering the last ones, then on command I have the average calculated and from this reference curve, I let the operator choose whether they want the two upper and lower (window) curves to be created automatically, of tolerance, and then correct them manually, or whether to use the average curve and from this define the the acceptable surround.

With a few lines of SCL and a few HMI pages, I leave it all parameterizable by the end user, for them to repeat the procedure whenever they want.

I don't know if it fits with what you need.

Thank you for your reply!

Yes indeed this is what I'm looking for. (solution of Einstein) I think this solution should work for me.

As a basic reference for now, we just want to use a linear interpolation. I will have a look at the LGF function anyway (thanks for the tip)

The problem with the excel solution is that we actually create this curve online in the PLC. the commissioning engineer measures values during commisioning and adjusts the curve table in a live situation. Once finished I'll have to store this table from the standard program into the safety program.

thanks guys!

Best regards,

Bram

To simplify the process for your service engineer, consider allowing them to input 10 or 20 key data points and then use linear interpolation to generate the full array of 1,000 integers. This approach reduces manual data entry and ensures smooth transitions between specified points.

Implementing Linear Interpolation in TIA Portal

Siemens provides resources on performing linear interpolation within TIA Portal. For example, the article "Interpolating measured values with polygon and output of function values" details how to execute linear interpolation via measured values and output new function values based on this polygon.

Alternative Approach

If you're open to using external curve fitting tool allows you to input a limited set of data points and perform interpolation to generate a smooth curve. You can then export the interpolated data and import it into your TIA Portal project.