Datalogic PowerScan M8500, Product Reference Manual

Page: 159 / 233

References
156 PowerScan® M8500
ACK/NACK Protocol
PowerScan
®
M8500 Readers
The transmission protocol takes place between reader, cradle and Host. The reader passes its
data (code read) to the cradle, which sends it to the Host. The management of responses
(from Host or cradle) depends on the Transmission Mode parameter, see
page 171
.
In the following descriptions the completed transmission is indicated by the Beeper Control
for Radio Response parameter with its default setting to Normal, see
page 171 .
When ACK/NACK is disabled (in One-Way tx mode), there is no control from cradle to
Host transmission, the reader responds with the good reception tone.
Figure 25. ACK/NACK disabled
Figure 26. ACK/NACK enabled
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
BC-80X0 does the reader respond with the good reception tone .
If the BC-80X0 does not receive an ACK or NACK, transmission is ended after the RX
Timeout, see
page 157
. See also Radio Protocol Timeout,
page 170
.
When ACK/NACK protocol is enabled, FIFO must be disabled manually, see below.
FIFO
PowerScan
®
M8500 Readers
If enabled, the BC-80X0 collects all messages sent by PowerScan
®
M8500 and sends them
in order of acquisition to the connected Host.
If disabled, PowerScan
®
M8500 blocks message transmission until the BC-80X0 has
completed transmission towards the Host.
BC-80X0
Host
data
cable
PowerScan
®
M8500
data
Transmission Mode = One-Way
good RX
beep
BC-80X0
Host
data
cable
PowerScan
®
M8500
data
NACK
ACK
good RX
beep
Transmission Mode = Two-Ways
data