Hi

How can I convert String Value to Real ?

I used String to Real function to convert, I have already had Real value but PLC only display positive value. PLC did not display negative value as same as the Weighing Indicator .

Weighing = 0.0 --> PLC display 0.0

weighing = 0.1 or higher --> PLC display the same

weighing = - 0.1 or lower --> PLC still display 0.0 . How can PLC display as same as the Weighing Indicator  

thanks.

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Split from How to read value from weighing scale to S7-200.

Hi,

in Step 7 V5.5 you can use IEC standard functions for converting. FC39 converts String to REAL but the String needs a special format...

Please check this:

https://support.industry.siemens.com/cs/de/en/view/10913338

Regards,

Towome

jacek d

Show us the code or better online view screenshot.

 hi

pls see the attached pic to understand my problem, VB1 = string, VB30 = string , VD100 = REAL

thanks 

Silam

 

jacek d

Show us the code or better online view screenshot.

 hi

pls see the attached pic to understand my problem, VB1 = string, VB30 = string , VD100 = REAL

thanks 

Silam

 

Silam

 

jacek d

Show us the code or better online view screenshot.

 hi

pls see the attached pic to understand my problem, VB1 = string, VB30 = string , VD100 = REAL

thanks 

 

Towome

Hi,

in Step 7 V5.5 you can use IEC standard functions for converting. FC39 converts String to REAL but the String needs a special format...

Please check this:

https://support.industry.siemens.com/cs/de/en/view/10913338

Regards,

Towome

 hi

thanks for your suggestion, but unlucky I'm using S7-200 so Step 7 V5.5 is not available to me.

Have you got any idea using S7-200 ? 

best regards

Try to remove the blanks between the sign and the number in the string.

Update. After RTFM I've found this:

The Substring to Real instruction converts strings with the

following form: [spaces] [+ or -] [digits 0 - 9] [. or ,] [digits

0 - 9]

jacek d

The Substring to Real instruction converts strings with the

following form: [spaces] [+ or -] [digits 0 - 9] [. or ,] [digits

0 - 9]

hi

My application is received data from Weigh scale to S7-200 in freeport mode, PLC receive 22 bytes

data from weigh scale  and put to PLC buffer memory ( same as weigh scale data format ).

so, each byte contain 01 value and space " " is a value received from weigh scale. In py opinion, can 

not change value space " " between sign and digits, there must have other way to solve it 

pls see the atached pic for more details, 

best regards