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<== Date ==> <== Thread ==>
Subject: the cheksum of Streamdevice
From: 于春蕾 <[email protected]>
To: [email protected]
Date: Tue, 23 Apr 2013 21:17:43 +0800 (GMT+08:00)
Hi all,
Recently I try to use Streamdevice to control a power supply, but the protocal of this power supply is very special, especially the check. 
The checksum is similar to LRC but different, here is the example.
       Field name                    ASCII                                Hex
        start character                          :                                       3A
        slave address                          01                                   30 31
        command code                        03                                   30 33
        read data1 high                       04                                   30 34
        read data1 low                         01                                   30  31
        read data2 high                       00                                   30 30
        read data2 low                         01                                   30 31
        LRC checksum                         F6                                  46 36
        End mark                                 CR LF     ;                         0D 0A
The calculation of LRC checksum is as followed. First, SUM =01+03+04+01+00+01=0a(hex). Then, LRC checksum is the negative of SUM, so the checksum is F6(ASCII). I use %<01negsum>, but the calculation of SUM is 30+31+30+33+30+34+30+31+30+30+30+31, so the checksum is error. According to %<hexsum>, I want to try %<01hexnegsum>, but it shows unkown cheksum algorithm. What can I do with this kind of checksum, I am so anxious.
Thanks very much and best wishes!
                       Chunlei




Replies:
Re: the cheksum of Streamdevice Dirk Zimoch
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