Avlink HRM-602P - Manual (Page 52)

H H H R R R M M M - - - 6 6 6 0 0 0 2 2 2 P P P
51
CRC Calculation
CRC 0 = 0 (initial value)
CRC 1 = CRC_ TABLE [CRC 0 ^ Byte 1] = CRC_ TABLE [0x00 ^ 0x20] = 0x23
CRC 2 = CRC_ TABLE [CRC 1 ^ Byte 2] = CRC_ TABLE [0x23 ^ 0x01] = 0x9F
CRC 3 = CRC_ TABLE [CRC 2 ^ Byte 3] = CRC_ TABLE [0x9F ^ 0x06] = 0x8D
CRC 4 = CRC_ TABLE [CRC 3 ^ Byte 4] = CRC_ TABLE [0x8D ^ 0x03] = 0x93
D-2 Device ACK Packet
When the device receives supported commands comes from the host, and then will
response with following ACK:
Table – ACK Type List
Ack Type Byte 1 Byte 2 Byte 3 Byte 4 Byte 5 Byte 6 … Last Byte
Type A AB CB
Type B AB LB Index 1 Value 1 Index 2 Value 2 … CB
Type C AB LB Data 1 Data 2 CB
Type D AB LB INF OP IP Name 1 … CB
Type E AB LB EXINF VEINF AEINF PLUG … CB
D-2.1 ACK Type A
ACK Byte + CRC Byte (Total 2 Bytes)
Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
AB ACC 0 0 Device ID (0 – 31)
CB CRC
ACC: The devices acknowledge status. Accept or Reject.
1: device accepts this request. (ACK; acknowledge)
0: device rejects this request. (NAK; negative acknowledge)
 The device sends the Nak packet is always 2 bytes. (NAK + CRC)
0: Reserve, Always 0.
1: Identifier, Always 1.
Device ID: Device id ranges from 0 to 31. (Please refer to device’s user manual)
CRC: Device always sends the CRC code to follow the last byte.