FUJITSU M304X - Manual (Page 94)

6.4 Message Protocols
The following protocols have been prepared for this printer:
. XON/XOFF protocol
. Reverse Channel line (pin protocol
. DTR line protocol
. RTS line protocol
The protocols above report the interface buffer state (almost empty or almost
full) to the host and operate according to the printer start/stop state.
6.4.1 XON/XOFF protocol
The XON/XOFF protocol transmits code or code the
host via the TD line under the following conditions:
Conditions for XON transmission
DTR is turned from off to on (0).
The interface buffer is empty or almost empty.
Conditions for XOFF transmission
The interface buffer is almost full, or
Before DTR is turned from on to off.
The time from when XOFF is transmitted to when DTR is turned from on to off is
0.5 (for 19.2 or 9.6 K baud) or 1 (for 2.4 or 4.8 K baud).
For timing details, see Figures 6.5 and 6.6.
6.4.2 Reverse Channel line protocol
When the Reverse Channel signal is on the host can transmit data.
This signal is turned from off to on under the same conditions under which the
protocol transmits code XON.
This signal is turned from on to off under the same conditions which the
XON/XOFF protocol transmits code XOFF.
For timing details, see Figures 6.3 and 6.4.
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