Unitech MR350MKII manual Host Transmissions, Terminal Transmissions, Protocol Operation

\	convert to	\\
00 hex -- 1F hex	convert to	\ 80 hex -- \ 9F hex
A0 hex -- FF hex	convert to	\ 20 hex -- \ 7F hex
(excluding DC hex)

2)one-byte data transmitted as original data without converting

other codes	unchanged
Host Transmissions
Transmission	Format
Poll	STX, ADDR
Host Data	STX, CMD, data, CS1, CS2, ADDR
Acknowledgment	ACK
Negative ACK	NAK
Terminal Transmissions
Transmission	Format
Terminal Data	STX, data, CS1, CS2, ETX
Acknowledgment	ACK
Negative ACK	NAK

4.4.1.Protocol Operation

The terminal protocol operates as a multi-point stop and wait protocol. A station sends only one frame and then stops and waits for a response.

The following scenarios typify link transmissions (Poll):

* Terminal has no data for the host:

=> STX ADDR

<= EOT - if no data is ready for transmission

* Terminal has data for the host:

=> STX ADDR

<= STX <data> CS1 CS2 ETX - if data is ready

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