Hii Albis,

I have one 3rd  party modbus device which successfully connected in Xwp . All the values coming in integer formats which i need to convert in real  formats as per process requirements .

unfortunately i could not found integer to real block (I_R )in x works library v5.1.

any solution ?

thanks ,

deepak

Hi deepak123,

Please take a closer look at the catalog applet in CFC. Some Firmware blocks are listed in the tab "Blocks" and some in the tab "Libraries". You find the FB I_R in the tab Blocks / CONVERT

best regards,
swissborder

Hi swiss ,

Thanks for your feedback .

unfortunately i m using CFC V8.0+upd1 there which i could not found I_R blocks ..

what should  i do ?

thanks ,

deepak

Hello Deepak;

Please tell us: are the values you recieve over Modbus in integer format, or are they half of a REAL variable?

Cn you read the data as understandable integer values? What numerical value do you see wen you open each one?

Normally Modbus will operate on 16-bit values per reister, which means that in order to send a REAL (floating-point) value it requires 2 (consecutive) registers. Usually you doi not try to convert the 2 integers to a RAL value, you simply read the 2 integers as a single REAL value.

So if your Modbus slave sends you a REAL value in addresses 40001 and 40002, transfer them to a single 32-bit register and interpret them as REAL.

If the bytes have not been swapped you should see a correct floating-point value. If you read an impossible value (say 1.03 e-27) try rearraging the byte order of the original registers. This is called the BIG ENDIAN problem, and is explained fiurther in the following FAQ (this document  uses a S7-200 as an example, but is applicable to any PLC, although the byte changes might have to be done by your program):

How can you convert a big-endian word or double-word into a little-endian word or double-word and vice versa?

https://support.industry.siemens.com/cs/fr/en/view/29155499

Hope thois helps,

Daniel Chartier

New question published by derioeng is split to a separate thread with the subject How can convert 2 "(W#16#0)" in floating point in the S7 300?.

Best regards
Jen_Moderator