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Data transmission may accidentally involve various types of errors. The BHT-Ir proto-
col is designed to recover from those errors as frequently as possible. What follows is
the BHT-Ir protocol for phases 1 through 3.
Phase 1: Establishment of Data Link
■ Normal phase 1
The sending station transmits a sequence of DLE ENQ and IDm (sending station's
ID) to the receiving station. Upon receipt of a sequence of DLE ACK and IDs
(receiving station's ID) from the receiving station, the sending station shifts to
phase 2.
To phase 2.
Receiving station
Sending station
■ Phase 1 with iterated transmission of DLE ENQ and IDm due to no re-
sponse or invalid response
If the sending station receives no response or any invalid response from the
receiving station in response to the sent sequence of DLE ENQ and IDm, it iterates
sending of the sequence at 0.5-second intervals up to 60 times.
If the sending station receives a sequence of DLE ACK and IDs before sending the
sequence of DLE ENQ and IDm 60 times, it shifts to phase 2.
DLE ENQ and IDm
DLE ACK and IDs
Sending
station
Receiving
station
To phase 2.
DLE ENQ and IDm
DLE ENQ and IDm
DLE ENQ and IDm
DLE ACK and IDs
0.5 second
0.5 second
TIP
You may modify the number of iterations of a sequence of DLE ENQ and IDm
for the sending station. The default is 60 times at 0.5-second intervals. For
details, refer to the SET PROTOCOL screen in System Mode (pp. 54 and 56)
and the XFILE statement given in "BHT-BASIC Programmer's Manual."