CHAPTER 4: Operation

Data Flow — A/S-2G to Asynchronous Device

Bisynchronous Device

A/S-2G Converter

Asynchronous Device

Send data block D

NAK

Send data block D

ACK 0

when available

Send block D

If data not properly received by A/S-2G:

Send data block E

NAK

Retransmit block E

ACK 1 (when

correctly received)

Send block E

If data not yet available from synchronous device while synchronous line to A/S-2G is engaged:

2-second interval from previous ACK

TTD

NAK

2-second interval

TTD

NAK

Continues until data available

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Black Box PCW22A-R4, PCW22A-R3 manual Operation