Denso BHT-7500S, BHT-7500W user manual 186

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.

Sending station

DLE ENQ and IDm

Receiving station

DLE ACK and IDs

To phase 2.

■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.

Sending station

0.5second

0.5second

DLE ENQ and IDm	Receiving
	station
DLE ENQ and IDm
DLE ENQ and IDm

DLE ACK and IDs

To phase 2.

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. 62 and 64) and the XFILE statement given in "BHT-BASIC Programmer's Manual."

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