SLAU358Q September 2011 – October 2019
After the prompt byte (0x3E) and the command identification byte CMD, the frame length bytes L1 and L2 (which must be equal) hold the number of bytes following L2, excluding the checksum bytes CKL and CKH. Bytes A1, A2, A3, A4, LL, LH, and D1 to Dn are command specific. However, the checksum bytes CKL (low byte) and CKH (high byte) are mandatory. If the data frame is received correctly and the command execution is successful, the acknowledge byte ACK (0x90), in progress byte (0xB0) or received message with header byte (0x80) as the first one. Incorrectly received data frames, unsuccessful operations, and commands that are not defined are confirmed with a DATA_NACK = 0xA0.