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Protocols, Memory mode xon/xoff, Memory mode robust xon/ xoff – Dascom LA550W User Guide User Manual

Page 135: Memory mode robust xon/xoff

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User guide

Interfaces

127

Protocols

Memory mode XON/XOFF

The received characters are stored in a FIFO buffer (first in/first out).
The characters are processed in this buffer.

The buffer capacity can be adjusted from 0 to 64 Kb.

If the buffer is full, the interface signals NOT READY (signal acknow-
ledgement: Level 1, -12 V) and XOFF (hex. 13, dec. 19). This results
in stopping the data transmission. When the FIFO buffer is empty
again, the interface signals READY (level 0, +12 V) and XON (hex.
11, dec. 17). Data transmission can be continued.

In addition, the READY signal is influenced by the status of the prin-
ter (On/Off Line). If the printer assumes an undefined state, the in-
terface also signals NOT READY and XOFF.

Memory mode Robust XON/
XOFF

Robust XON/XOFF is similar to XON/XOFF. However, the state of
the printer (XON or XOFF) is also periodically transmitted via the
TxD line in the case of Robust XON/XOFF.

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