Texas Instruments HFDEMOKITII 用户手册
September 2001
S6350 Reader Reference Guide
19
3.1.4 Command Flags Response
The command flags in the response packet report the actions of the reader. The meanings of
the bits are defined below.
the bits are defined below.
Bits 0-3
Reserved for future use.
Bit 4
Error flag. If this flag is set the command was unsuccessful and the
data section of the response packet contains the error code. (See
section Appendix B for a list of error codes.)
data section of the response packet contains the error code. (See
section Appendix B for a list of error codes.)
Bits 5-7
Reserved for future use.
3.1.5 BCC
A Block Check Character (BCC) is used for error detection and is attached to the end of the
packet. The 16 bit BCC is calculated on all the bytes of the packet including the SOF. The BCC
consists of two parts: the LSbyte is a Longitudinal Redundancy Check (LRC) and the MSbyte is
the ones compliment of the LRC. The LRC is calculated by performing a cumulative Exclusive-
OR operation on all the bytes of the packet.
packet. The 16 bit BCC is calculated on all the bytes of the packet including the SOF. The BCC
consists of two parts: the LSbyte is a Longitudinal Redundancy Check (LRC) and the MSbyte is
the ones compliment of the LRC. The LRC is calculated by performing a cumulative Exclusive-
OR operation on all the bytes of the packet.
3.1.6 Example Request Packet
01
hex
SOF
0A
hex
LSbyte of length
00
hex
MSbyte of length
00
hex
LSbyte of node address
00
hex
MSbyte of node address
00
hex
Command flags (Not addressed)
02
hex
Command (Tag-it
TM
Read block)
01
hex
Data (Block number 1)
08
hex
LSbyte of Checksum
F7
hex
MSbyte of Checksum