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Technical support / CRC problems
« on: December 17, 2011, 03:12:03 PM »
I am writing on a nano a communications package that will talk to a Heatmister RS485 room stat. I have the communications working fine except I am having trouble with the CRC CCITT (0xFFF) checksum. I have to use an online calculator to find the CRC and enter it by hand. What I need is to be able to calculate in the code the CRC. The built in CRC16 in TBASIC give the wrong answer. Has someone done this and can help. Example of data frame is ? 03 0A 81 00 00 00 FF FF? and then I add a CRC of ?8A 86? low byte then high byte.