Symbol SE 923, Руководство по интеграции

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Simple Serial Interface
Example of a problem which may occur when ACK/NAK handshaking is disabled:
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The host sends a PARAM_SEND message to the decoder to change baud rate from
9600 to 19200
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The decoder cannot interpret the message
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The decoder does not implement the changes requested by the host
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The host assumes that the parameter changes have occurred and acts accordingly
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Communications are lost because the change did not occur on both sides.
If the ACK/NAK handshaking is enabled, the following occurs:
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The host sends a PARAM_SEND message
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The decoder cannot interpret the message
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The decoder CMD_NAKs the message
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The host resends the message
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The decoder receives the message successfully, responds with CMD_ACK, and
implements parameter changes.
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.
Note: When decode data is transmitted as raw ASCII data, then 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