SSI Interface 5 - 5
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.
ACK/NAK Disabled and Unpacketed ASCII Data
The decoder sends captured data to the host.
Communication Summary
RTS/CTS Lines
All communication must use RTS/CTS handshaking as described in the Simple Serial Interface Programmer’s
Guide, p/n 72E-40451-xx. If bypassing hardware handshaking, the host must send the WAKEUP command before
all other communication or the first byte of a message can be lost during the scanner wakeup sequence. Zebra
recommends not bypassing RTS/CTS hardware handshaking.
ACK/NAK Option
ACK/NAK handshaking is enabled by default and Zebra recommends leaving it enabled. Disabling this can cause
communication problems, as handshaking is the only acknowledgment that a message was received correctly.
ACK/NAK is not used with unpacketed decode data regardless of whether it is enabled.
Number of Data Bits
All communication with the scanner must use 8-bit data.
Decoder
Data is captured
by decoder
Host
(1)
DECODE_DATA
message sent
Decoder
Data is captured
by decoder
Host
(1)
ASCII data sent
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