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CRC value is received with the frame. It is needed for checking the cable
connection between the WRAP and the HOST. This checking is necessary only
when the RS232 cable connection is > 25 m.
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The processing of two similar messages must be avoided in the HOST
application. Depending on CRC, MN (message number) and ID (own IP
number) values can be checked to detect if the frame is the same as the one
already in process.
4.4.4 The HOST application handles the frame
HOST application handles the frame data. The HOST application must have
the commID number of the Hand Terminal during the whole data processing
time so that application is able to answer to the correct Hand Terminal.
4.4.5 HOST sends an answer to the Hand Terminal via WRAP
When the HOST application has processed the Hand Terminal’s frame it sends
an answer to the Hand Terminal of the frame according to the command HOST
RF650 protocol.
It is recommended that the HOST application is programmed to keep in
memory the last frame sent for each Hand Terminal, so that the host can
answer any retransmission requests of Hand Terminals as quickly as possible.
4.4.6 The WRAP sends the frame to the Hand Terminal
When the WRAP has received the frame from the HOST it does the following:
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The CRC is checked
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A frame is sent to the Hand Terminal.
4.4.7 The Hand Terminal receives a frame from the WRAP
When the Hand Terminal has received the frame from the WRAP it does the
following:
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The CRC is checked
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Frame commands are executed
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A short beep is generated.
4.4.8 Transaction End
The Hand Terminal and the W RAP are ready for a new transaction.