Siemens Step 7 Convert

RheinhardtP · Apr 28, 2006

Hi All,

I'm currently busy on a project where i must take a number of char type objects and convert them to a decimal number for comparison reasons.

i tried the standarD Step 7 STRNG to INT conversion with no good values.

I understand the string concept like following.

Variable type STRING[5]

STRING[ABCDE]

byte 0 Max No of Char
byte 1 Actual amount in String
byte 2 A
byte 3 B
byte 4 C
byte 5 D
byte 6 E

Is there any tip or trick to getting this conversion going

I would really appreciate any help.

If there are any requests i'll post my code on this topic.

Kind Regards

Rheinhardt

Ken M · Apr 28, 2006

Hi Rheinhardt

What values do you have in Bytes 0 and 1? You may have to load these with something between 1 and 6 (or in your case 1 and 5) to ensure the STRING variable is correctly recognised. For example if these bytes contain 0 then no conversion will take place.

Are you sure the STRING value can be represented as an INTEGER? Is it within the bounds for an INTEGER data type?

Regards

Ken

SimonGoldsworthy · Apr 28, 2006

I haven't used FC38 before, but here's the code I ran and checked in the simulator. In the first example I used a string variable in temp local data and fill the string in using the program, the second example uses a string defined in a DB. Note that the DB has to be in the symbol table.

Code:

	 LAR1 P##sValue				 //string data type in temp area
	 L	 5
	 T	 B [AR1,P#0.0]
	 L	 4
	 T	 B [AR1,P#1.0]
	 L	 '1'
	 T	 B [AR1,P#2.0]
	 L	 '2'
	 T	 B [AR1,P#3.0]
	 L	 '3'
	 T	 B [AR1,P#4.0]
	 L	 '4'
	 T	 B [AR1,P#5.0]
	 CALL FC	38
	 S	 :=#sValue
	 RET_VAL:=#iValue
 
	 CALL FC	38					//string declared in a DB
	 S	 :="dbStrings".String1
	 RET_VAL:=#iValue

RheinhardtP · May 1, 2006

Structure

Dear Ken,Simon

Thanks for your replies.
Ken,
I load the values into my 1st and second byte . Since my string is defined in a data block as value == string[5] it loads the first byte automatically. I have loaded the value 5 into my second byte, but even with a value of '00000' i get INT 20000.

My STRING VALUE is defined as follow.

VALUE String[5]

byte 1 2 3 4 5 6 7
16#05 16#05 '1' '9' '4' '6' '3'

My return out of FC38 os then 20000. strange I will try your tips when i get to the office and post my code.

Simon you never said your result in the similator was it sucesfull??

Thanks again

Rheinhardt

SimonGoldsworthy · May 1, 2006

Yes, it gave the expected results.

Siemens Step 7 Convert

RheinhardtP

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Ken M

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SimonGoldsworthy

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RheinhardtP

Lifetime Supporting Member + Moderator

SimonGoldsworthy

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