Siemens DCS Question

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Thread Starter

Bob Peterson

For anyone out there who knows something about the current line of Siemens DCS's.

Yesterday I received an email from an end user to the effect that their Siemens DCS is unable to read floating point values out of the SLC5/05 we supplied. I am curious why this would be so.

Last week I was at a customer site that uses ABB. They too told me that it was unable to read floating point values.

Just out of curiousity - why would anyone create a DCS that cannot deal with floating point numbers? Or is this just a poorly constructed driver?

Bob Peterson

US Filter, Rockford Number 815-877-3046 X57
 
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Hakan Ozevin

> Yesterday I received an email from an end user to the effect that their Siemens
> DCS is unable to read floating point values out of the SLC5/05 we supplied.
> Just out of curiousity - why would anyone create a DCS that cannot deal with
> floating point numbers? Or is this just a poorly constructed driver?

"Deal" and "read". The key points for your question. Of course those DCS systems "deal" (use internally) real/foating point numbers. The problem in your case is "reading" a floating number from a third party device may result to false figures. I can understand this because I know at least four different versions of real number format (although it should be standard!!).

I can suggest:
1) Tell them to use integer format (only two versions, i.e. most significant byte on the left side or least significant byte on the left side!!).
2)Someone can "swap" and interprete one's real number data to the other's real number format. Check such a conversion from your side or their side.
 
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david mertens

Siemens uses 32 bit IEEE floating point numbers in the PCS7 and S7 product range. However the memory is organised in words and not in bytes, this may lead to the switching of two bytes in the 32 bit order. Hope this helps.
 
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