ThingMagic M5e-Compact - Manual (Page 58)

Format for Microprocessor Reply to Host
58 Overview of the Communication Protocol
Format for Microprocessor Reply to Host
There are three different types of replies that the microprocessor can make to the host as
follows:
Acknowledge that the command was properly processed (ACK)
Return a fault code
Provide data that is requested by the host
This section describes each of these three types.
Unless otherwise specified, all commands return, as part of the Reply message, a status
word with an ACK or a Fault. Those commands that return a Data Reply message are
clearly shown.
Microprocessor ACK Message
Many of the commands require the microprocessor to perform a function, but do not
require the microprocessor to send data back to the host. However, since the host cannot
send a message until the microprocessor replies, an ACK is sent.
The ACK message contains no data. It returns the same OpCode that was sent originally
to the microprocessor, sets the Status Word to 0x0000 (zero) and the Data Length to
0x00 (zero).