[?]: MM440 profibus Communication

SIMATIC S7-200/300/400, Step7, PCS7, CFC, SFC, PDM, PLCSIM,
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Joined: Tue Dec 28, 2010 2:11 pm

[?]: MM440 profibus Communication

Post by saravanan_tsvk » Thu Sep 15, 2011 12:57 pm


I am working on a project where I need to communicate between MM440 and S7 PLC via profibus.

I have established the communication and configured the MM440 in Hardware configuration with 4 PZD's ( Process Data's).
The P2051 ( PZD to CB) is configured in such a way thats the structure of 4 words are,

Code: Select all

1st word = Status word
2nd word = Actaul Frequecny
3rd word = Actual Current
4th Word = Output Voltage
I am getting the values in the Process data words which is in the IEEE format and that cannot be directly shown in the HMI & SCADA.

For Example I am getting value 6048 in the 3rd word, but the actual current is 1.4 A.

Can anyone please help me to find a solution for converting the IEEE format into Real format. If possible please upload the program to convert the IEEE to Real.

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Joined: Fri Nov 16, 2007 3:18 pm
Location: Europe

Re: [?]: MM440 profibus Communication

Post by kriztof » Fri Sep 16, 2011 8:55 am

First, you try to read double word value (Real and IEEE are 32-bit) into single word (PZD is 16-bit).
Second, I think you have to use PKW mechanism instead of PZD data words.
Check this document
https://support.automation.siemens.com/ ... 0202_I.pdf

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