ThingMagic M5e-Compact User Manual
Page 54
Host-to-Reader Communication
54
Overview of the Communication Protocol
The fields are summarized in the following table.:
Field
Length
Description
Header (Hdr)
1 byte
Defines the start of the packet. Equal to 0xFF
1
Data Length (Len)
1.Minimum packet length is 5 bytes; the maximum packet length is 255 bytes.
1 byte
Defines the length,
N
, of the data field contained in the
packet.
Command
1 byte
Specifies the command that the reader is to execute.
Data
N
bytes
(0 to 250)
Defines the binary data required by the reader for use with a
command. This could, for example, represent transponder
data to be written. The length,
N
, can vary between 0 and
250 bytes.
CRC-16 Checksum
(CRC HI, CRC LO)
2 bytes
CRC-16 checksum (high order byte first). CRC polynomial is
CCITT CRC-16, with a preload of 0xFFFF. This does not fully
specify the operation of the CRC, see
.