Skip to Content

Register Login

Industry Online Support

Technical Forum

Navigation

Compare Arrays of Chars

Created by: TimB2011 at: 12/27/2010 7:18 PM (8 Replies)

Rating (2)

Thanks 4

9 Entries

12/27/2010 7:18 PM	Rate (0)
TimB2011 Posts: 4 Rating: (0)	I receive an Array of Characters from an OPC Server. I would like to monitor when the Array of Characters has been recieved by monitoring when one of the Chars changes from ' ' ('32' or space - the cleared state) to another ASCII character such as 'A' or '9'. I assume I need to convert the Char byte to an Integer and then use the Comparison INT to INT but do not know how to convert the CHAR byte to INT. Block Move ??? Thanks
TimB2011 Posts: 4 Rating: (0)
Suggestion To thank Quote Answer

12/27/2010 8:47 PM	Rate (0)
hdhosseini Diamond Expert Joined: 1/28/2009 Last visit: 9/10/2024 Posts: 6849 Rating: (1365)	Dear member This type occupies one byte and represents a single character in form of ASCII format.If you want to search a table for specified charcter or To compare a byte (char), you can use simple integer compare. [code] L DB1.DBB 0 L 'a' ==I = Q 0.0 ////////////////// L DB1.DBW 0 L 'ab' ==I = Q 0.1[/code] Best regards
	Demo Channel on Youtube
Suggestion To thank Quote Answer

12/27/2010 9:19 PM	Rate (0)
TimB2011 Posts: 4 Rating: (0)	I am new to Siemens Step 7 and I am only familiar with ladder logic, FB and DB at this point and not that great at these. I understand your response logically but not how to actually do it with Step 7. Can I simply use the Integer Comparotor ladder instruction?
TimB2011 Posts: 4 Rating: (0)
Suggestion To thank Quote Answer

12/27/2010 9:55 PM	Rate (0)
hdhosseini Diamond Expert Joined: 1/28/2009 Last visit: 9/10/2024 Posts: 6849 Rating: (1365)	Dear member It is totally similiar.check the attachment.But I prefer STL. BR Attachment result.JPG (2085 Downloads)
	Demo Channel on Youtube
Suggestion To thank Quote Answer

12/27/2010 10:41 PM	Rate (0)
TimB2011 Posts: 4 Rating: (0)	Okay - getting closer. I have an array of chars in DB555 starting at Byte 44 for 40 bytes. If I try to address DB555.DBB44 as an Input to the Integer compare it will not allow it. I have to address it as a Word DB555.DBW44 and then compare. I get two characters at one time not one?
TimB2011 Posts: 4 Rating: (0)
Suggestion To thank Quote Answer

12/28/2010 3:54 AM	Rate (2)
fritz Diamond Expert Joined: 10/7/2005 Last visit: 9/18/2024 Posts: 3020 Rating: (1054)	TimB2011 If I try to address DB555.DBB44 as an Input to the Integer compare it will not allow it. Hello TimB2011 gut feeling tells me that you "Type check of Addresses" ticked which causes this "problem". To solve it, open any Block, go to <Options> --> <Customize>,select the "LAD/FBD" tab in the popup and untick the"Type check of Addresses". The Editor will now allow youto compare bytes with the Integer comparator and I hope this helps.
	Cheers fritz The advice and opinion given in this thread is that of the author and does not necessarily reflect the views of I S Systems Pty Limited. To find out how I S Systems can help you with your automation needs please visit www.issystems.com.au.
Suggestion To thank Quote Answer
This contribution was helpful to 2 thankful Users TimB2011 vipz

12/28/2010 5:10 AM	Rate (0)
hdhosseini Diamond Expert Joined: 1/28/2009 Last visit: 9/10/2024 Posts: 6849 Rating: (1365)	Hello TimB2011 Another possible way to move one byte character to an integer TEMP area and compare two integers as shown in the attachment. Best regards Attachment CHAR.JPG (1087 Downloads)
	Demo Channel on Youtube
Suggestion To thank Quote Answer

12/28/2010 5:58 AM	Rate (0)
fritz Diamond Expert Joined: 10/7/2005 Last visit: 9/18/2024 Posts: 3020 Rating: (1054)	hdhosseini Another possible way to move one byte character to an integer TEMP area and compare two integers ... And another possible way is to move one byte character to a Double Integer TEMPand compare two Double Integers (or perhpas evenfurther convert them to a REAL and then do a REAL comparison). Thequestion though is: Why would you? Call me old fashioned dear hdhosseini, but I find the creation of additional TEMP's and MOVE's leads to a wasteful andinefficient programming style with no benefits, wouldn't you agree (moreso since your orignal STL logic was spot on)?
	Cheers fritz The advice and opinion given in this thread is that of the author and does not necessarily reflect the views of I S Systems Pty Limited. To find out how I S Systems can help you with your automation needs please visit www.issystems.com.au.
Suggestion To thank Quote Answer
This contribution was helpful to 1 thankful Users hdhosseini

12/29/2010 9:14 PM	Rate (0)
TimB2011 Posts: 4 Rating: (0)	"Type check of Addresses" Unchecking this solved my issue Thanks
TimB2011 Posts: 4 Rating: (0)	Last edited by: TimB2011 at: 12/29/2010 9:16 PM
Suggestion To thank Quote Answer
This contribution was helpful to 1 thankful Users fritz

|

Share this page:

Share this page on...

Follow us on