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5
Transmission Mode = Two-Ways
DRAGON M
When ACK/NACK is enabled (in Two-Way tx mode), the Host sends an ACK
character (06 HEX) in the case of good reception or the NACK character (15 HEX)
requesting re-transmission, in the case of bad reception. Only after the ACK
character is received by the OM-DRAGON™ does the reader respond with the good
reception tone.
If the OM-DRAGON™ does not receive an ACK or NACK, transmission is ended
after the RX Timeout, see par. 5.1.4. See also Radio Protocol Timeout, par. 5.8.1.
Selection of the ACK/NACK protocol temporarily disables FIFO buffering see par.
5.1.3.
5.1.3
FIFO
DRAGON™ D Readers
This parameter determines whether data (barcodes) are buffered on a First In First
Out basis allowing faster data collection in certain cases for example when using
slow baud rates and/or hardware handshaking.
If the FIFO buffering is enabled, codes are collected and sent out on the serial line in
the order of acquisition. About 800 characters can be collected (buffer full), after
which the reader signals an error and discards any further codes until the
transmission is restored.
If the FIFO buffering is disabled, each code must be transmitted before another one
can be read.
DRAGON™ M Readers
If enabled, the OM-DRAGON™ collects all messages sent by DRAGON™ M and
sends them in order of acquisition to the connected Host.
If disabled, DRAGON™ M blocks message transmission until the OM-DRAGON™
has completed transmission towards the Host.
140
data
OM-DRAGON™
good RX
beep
ACK/NACK enabled
data
cable
NACK
data
ACK
DRAGON™
Host
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