Here is a different example from the manual. For better results we will use the broadcast ID. This way it doesn't matter what ID the DVR is set to.
0x85 (length) (This will always be 85) 0x7f (Receiver ID high byte) (This will always be 7F) 0x7f (Receiver ID low byte) (This will always be 7F) 0x4B (OPcode = key ) (This will always be 4B) 0x0B (DATA1 = "Play" keycode ) (This is the DATA from page 144) 0x59 (checksum) (Sum of all bytes AND 7F)
To calculate the checksum I suggest using Windows calculator in Scientific mode: 1. Add the first five bytes together. 2. If the sum is a 3 digit number, delete the left-most digit. 3. Using the AND operation on the calculator AND the sum with 7F.
So from the above example: 85+7F+7F+4B+0B= 1D9 We delete the left-most bit and our sum= D9. D9 AND 7F= 59 (This is the checksum)
