SIMPLE SERIAL INTERFACE
83
COMMUNICATION SUMMARY
RTS/CTS Lines
All communication must use RTS/CTS handshaking as described in
in Appendix A.
ACK/NACK Option
ACK/NACK handshaking can be enabled or disabled. This handshaking is enabled
by default; disabling this is not recommended as it can lead to communication
problems, since handshaking is the only indication that a message was received and
if it was received correctly. ACK/NACK is not used with unpacketed decode data
regardless of whether or not this option is enabled.
Number of Data Bits
All communication with the reader must use eight bit data.
Serial Response Timeout
The Serial Response Timeout parameter determines how long to wait for a
handshaking response before trying again, or aborting any further attempt
s.
Both the
host and reader should use the same value for this parameter.
Note:
A temporary change can be made to the Serial Response Timeout when the
host takes longer to process an ACK, or longer data string. Frequent permanent
changes are not recommended due to limited write cycles of non-volatile memory.
Retries
When sending data, the host should resend twice after the initial send if the reader
does not respond with an ACK or NACK (if ACK/NACK handshaking is enabled). If
the reader replies with a NACK RESEND, the host resends the data. All resent
messages must have the resend bit set in the Status byte. The reader resends data
two times after the initial send if the host fails to reply with an ACK or NACK (if
ACK/NACK handshaking is enabled).
Содержание Dragon D151
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