8 - 4 DS457-XX20004ZZWW Fixed Mount Imager Integration Guide
Transfer of Decode Data
The Decode Data Packet Format parameter controls how decode data is sent to the host. Set this parameter to
send the data in a DECODE_DATA packet. Clear this parameter to transmit the data as raw ASCII data.
ACK/NAK Enabled and Packeted Data
The imager sends a DECODE_DATA message after a successful decode. The imager waits for a
programmable time-out for a CMD_ACK response. If it does not receive the response, the imager tries to send
two more times before issuing a host transmission error. If the imager receives a CMD_NAK from the host, it
may attempt a retry depending on the cause field of the CMD_NAK message.
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.
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.
NOTE When transmitting decode data as raw ASCII data, ACK/NAK handshaking does not apply regardless of
the state of the ACK/NAK handshaking parameter.
Decoder
Data is captured
by decoder
Host
(1)
DECODE_DATA
(2)
CMD_ACK
message sent
Decoder
Data is captured
by decoder
Host
ASCII data
Decoder
Data is captured
by decoder
Host
(1)
DECODE_DATA
message sent
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