Transfer Of Decode Data - Symbol SE955 Integration Manual

10-28 SE955 Integration Guide

Transfer of Decode Data

The Decode Data Packet Format parameter controls how decode data is sent to the host. When this parameter is set, the data is sent
in a DECODE_DATA packet. When the parameter is cleared, the data is transmitted as raw ASCII data.
When decode data is transmitted as raw ASCII data, ACK/NAK handshaking does not apply regardless of
the state of the ACK/NAK handshaking parameter.
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 twice more 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.
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.
DECODE_DATA
Decoder
Data is captured by
decoder
CMD_ACK
message sent
Decoder
Data is captured by
decoder
(1)
Host
(2)
(1)
Host
ASCII data