Motorola Symbol MS4404 Integration Manual page 106

8 - 4 Symbol MS4404/MS4407 Integration Guide
ACK/NAK Enabled and Packeted Data
The decoder sends a DECODE_DATA message after a successful decode. The decoder waits for a programmable
time-out for a CMD_ACK response. If it does not receive the response, the decoder tries to send two more times
before issuing a host transmission error. If the decoder receives a CMD_NAK from the host, it may attempt a retry
depending on the cause field of the CMD_NAK message.
Decoder
Data is captured
by decoder
ACK/NAK Enabled and Unpacketed ASCII Data
Even though the ACK/NAK handshaking is enabled, no handshaking occurs because the handshaking applies only
to packeted data. In this example the packeted_decode parameter is disabled.
Decoder
Data is captured
by decoder
ACK/NAK Disabled and Packeted DECODE_DATA
In this example ACK/NAK does not occur even though packeted_decode is enabled because the ACK/NAK
handshaking parameter is disabled.
Decoder
Data is captured
by decoder
(1)
DECODE_DATA
Host
(2)
CMD_ACK
message sent
Host
ASCII data
(1)
Host
DECODE_DATA
message sent