Rice Lake Star SP298 Series Programmers Manual - Manual (Page 18)

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Outline of X-ON/X-OFF mode operations
This communication mode is set when dip switches 1 to 6 are set at OFF.
This mode notifies the host of X-0N (DC1) data when receiving is possible
and X-OFF (DC3) data when printing is not possible with the TXD signal.
The timing conditions for the output of X-ON and X-ON in the STAR mode
are set with the 4-C memory switch. When memory switch 4-C = 0 (set when
the unit is shipped from the factory,) only one byte is output by X-ON during
fluctuations from on-line (printer BUSY) to on-line (printer READY), and
only one byte is output by X-OFF during fluctuations from on-line (printer
READY) to on-line (printer BUSY). The same functions as above occur when
in the ESC/POS mode regardless of the 4-C memory switch setting.
When memory switch 4-C = 1, X-ON is output at regular three-second
intervals.
X-ON (DC1 with the control code name and 11H with hexadecimal display)
is output by the TXD signal line when the power supply is switched on and no
error occurs with the printer. The text data is transmitted to the RSD signal line
after the host has received X-ON.
X-OFF (DC3, 13H) is output when the empty area in the data buffer is less that
the prescribed number of bytes (*1: nearly full buffer condition.) Also, if
memory switch 4-C = 1, X-OFF is output for every byte of data received. The
host that receives X-OFF suspends text data transmission, but it is possible for
the printer to continue receiving data for the amount of space remaining in the
data buffer’s empty area at this point. If data that exceeds the amount of space
available in the empty area is transmitted, it will be discarded.
The empty area in the data buffer will increase as printing is carried out, and X-
ON is output if the amount of empty space in the data buffer is more than the
prescribed number of bytes (*2: near empty condition.)
*1 Refer to the nearly full buffer conditions for details on nearly full buffer conditions.
*2 Refer to the nearly empty buffer conditions for details on nearly empty buffer
conditions.
TXD
RXD
X–ON X–OFF X–ON X–OFF X–ON
Printing
Data Data Data