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Showing results for tags 'checksum'.
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I am working on calculating a checksum value for a command that is to be sent from an Allen-Bradley CompactLogix PLC to a Mass flow controller. An example of a command is the following: "@@@022SX!20.00;CHECKSUM". 1. The checksum is the sum of every characters' ASCII code value (starting from character 3). 2.Then this sum (which would be in decimal format) has to be converted to HexaDecimal 3. Finally, the last two characters of the result have to be extracted and that would be the value of the checksum. (For Ex: the value of every individual characters' ASCII code (starting from point 3) of the above command is 715. in HexaDecimal, 715 = 2CB. So , the value of the checksum for this command would be 2CB) I got to the point where i found the sum of ASCII code. Any idea on how to convert that to a HexaDecimal and then convert that HexaDecimal to a string so that I could concatenate it to the command string??
I am using TIA Portal V14 to program a Siemens Mobile HMI (KTP900 Mobile). I would like to pull up a program 'signature' from the HMI that would allow me to verify that the code in the HMI is the correct version. This would help prevent an accidental overwrite of old code, resulting in a single Mobile HMI that has differing code from several others that are also in use. The closest comparison would be a Safety Signature from a Safety PLC. However, I just want to use a file checksum or similar variable that I can put on my screen. Any ideas? I appreciate it.