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Binary values retained in text string


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I need to create a text string that will be used as a command to a serial I/O device. Content includes such things as: a command code e.g. Hex 60; a calculated length field,with the 8 least significant bits stored in one byte and the next 8 significant bits stored in another; and a byte that contains the cumulative XOR of all the preceding bytes. I figured out how to do the XOR thanks to a forum entry here, but when I try to build my text string, the numbers are converted to ASCII, e.g. the hex 60 (decimal 96) displays as two bytes with a value of 9 and 6, instead of one byte. Since the length must be calculated each time, I cannot use constants in the bytes. How do I get the right values in the bytes?

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FileMaker doesn't have a way to convert a number directly into its ascii code, you would need to make your own version of this.

One easy way I've done something similar is to have a global field (charCode) with 256 repetitions. Then use GetRepetition( charCode, 96 ) to give you the proper character for 96.

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Any suggestion for entering values into this array? I set it up as a table of its own instead of a repeating field, since it was easier to enter the data if I knew from the related numeric key which field I was entering. I have tried entering field values with the Alt key plus numeric key pad. All worked fine except the null (00), tab (09), line feed (0D), new record (0A). I also tried generating a tab-delimited file from a program that does allow bitwise manipulation of bytes. This worked fine except for some of the same characters, which of course were interpreted as delimiters and other non-data by the FM import function. I am going to need every value since they will be used to indicate calculated lengths, which may well be 9, 10, 12 or 13.

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Option-tab (maybe ctrl-tab on windows??) lets you enter a real tab into a field, otherwise you can cut/paste it from another app.

I think 0D/0A is going to be a problem, Pro is probably going to try to translate these to what your system uses when you output them, and translate to an internal form on input.

Similarly for 00, I doubt there is a way to enter this value directly.

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