MNC-0500-038
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Revision 2
Amplifier Communication and Protocol, XTRT, Touchscreen TWTA
Example of “Base 95”
Message (“ID/Version” Query): {A0}
1 Take Sum of Message Bytes
‘{‘ + ‘A’ + ‘0’ + ‘}’
123 + 65 + 48 + 125 = 361
2. Subtract 32
361 – 32 = 329
3. Modulus 95
329% 95 = 44
4. Add 32
44 + 32 = 76 (ASCII ‘L’)
Example of “Exclusive OR” Algorithm
Message (“ID/Version” Query): STX A 0 ETX (ASCII)
Progressively XORs the bytes to establish the check byte
Check byte = STX ^ A ^ 0 ^ ETX = ASCII character (may be non-
printable)
thus:
Table 3, Check Byte Calculation
“Base 95” 1. Take [Sum (all message bytes)] – 32 = C
2. Then take [Modulus C (“Base 95”)] + 32 = Result (Printable ASCII
character in range of 32 to 126)
“Exclusive OR”
XOR (all message bytes) = Result (non-printable byte)
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