RE: Asynch comm

The LRC doesn't include the STX. Only use the data and the ETX to calculate
the LRC.

Ken Slaugh  (707) 795-1512 x118
Chouinard & Myhre, Inc.
AS/400 Professional Administrator/MSE
Client Access Specialist
http://www.cm-inc.com/


                                                                                
                   
                    Chris Bipes                                                 
                   
                    <rpg@cross-check.co        To:     
"'MIDRANGE-L@midrange.com'"                 
                    m>                         <MIDRANGE-L@midrange.com>        
                   
                    Sent by:                   cc:                              
                   
                    owner-midrange-l@mi        Subject:     RE: Asynch comm     
                   
                    drange.com                                                  
                   
                                                                                
                   
                                                                                
                   
                    05/30/00 09:06 AM                                           
                   
                    Please respond to                                           
                   
                    MIDRANGE-L                                                  
                   
                                                                                
                   
                                                                                
                   



It is a check digit.  We use it here but I cannot post the code for
calculating the XOR check sum.  LRC stands for Longitude Redundancy Check.
Hint, check out the "C" math functions for using XOR and step thru the
string.  LRC includes the character immediately following the STX, X'02',
up thru and including the ETX, X'03'.  It is placed immediately following
the EXT.  It is best to translate your string to ASCII prior to adding the
STX,ETX,LRC.

EB:AS   XLATE  RESP        ASRESP
        EVAL   DATAOUT = STX + %TRIMR(ASRESP) + ETX
        EVAL   LRC = $LCR(DATAOUT)
        EVAL   DATAOUT = %TRIMR(DATAOUT) + LRC





Christopher K. Bipes     mailto:ChrisB@Cross-Check.com
Sr. Programmer/Analyst   mailto:Chris_Bipes@Yahoo.com
CrossCheck, Inc.         http://www.cross-check.com
6119 State Farm Drive    Phone: 707 586-0551 x 1102
Rohnert Park CA  94928 Fax: 707 586-1884


If consistency is the hobgoblin of little minds, only geniuses work here.
Karen Herbelin - Readers Digest 3/2000


     -----Original Message-----
     From: Jim Franz [mailto:franz400@triad.rr.com]
     Sent: Monday, May 29, 2000 11:51 AM
     To: MIDRANGE-L@midrange.com
     Subject: Asynch comm

     I am working on an AS/400 to a credit card authorization network.
     Unfortunately no previous AS/400 has previously certified to this
     network. I'm hoping someone else has seen this requirement for async
     communications. The specs from the other system call for me to add an
     LRC code at end of packet, "each record must be immediately followed
     by an LRC character that is computed by using the XOR function on each
     character of the record. This is a data integrity check." The network
     person on the other side is not able to really describe what it is.
     Sounds like some sort of check digit for the whole packet. Any ideas?
     Jim Franz



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