Well today at work I spend three and a half hours on the phone with a guy trying to install an upgraded version of a Mitel PBX System (A PBX System is used for by hotels to allow phone functionality in rooms) Basically the Property Management System send some byte via RS232 (serial port) and then the PBX accepts them and does whatever.
After hours I finally found out the problem we were sending 02415245594f55544845524503, but the PBX was expecting 024152455955544845524503. Now this may look like garbled crap to you. Which is true until you take into account that two digits are used to get the ASCII character. So the hex code 02415245594f55544845524503 actually translates to “AREYOUTHERE” which was incorrect for some reason they thought they should want the code 024152455955544845524503 which translates into “AREYUTHERE”.
Long story short, a “O” caused me a total headach, but looking back at the difference it seems stupid.