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Serial Interface
Serial Interface Operation
Nov93
Select the serial interface using the control panel keypad -
Local:
4-0--0-0-0-4-4, 0
until
Type:Serlal
shows, then
4.
See Chapter 2.
The serial interface accepts data at selectable rates from 300 to 38.4K bits
per second. Data can be received in 7- or 8-bit form with a variety of
start/stop and parity combinations.
When printing the high-speed font at 10 cpl and 133 characters a line
(counting an LF). the 800-lpm printer requires a sustained serial rate of
1774 characters per second. Using IO-bit serial characters requires a baud
rate of at least 19,200 for maximum throughput.
Important: The printer is provided with a number of interface strap options
(Appendix F) that can be used to supply feedback to the data source
regarding the printer's status. The way the printer reflects BUSY /READY
status is dependent on what the source expects to see. You must configure
the printer's interface firmware to match the method used by the source.
The printer can be strapped to generate a DC3 code (sometimes referred to
as XOFF) to reflect "BUSY" and a DC I (XON) code to reflect "READY"
conditions. The use of DCI and DC3 requires a full duplex communication
channel. since these codes are transmitted simultaneously with the receipt
of data.
The BUSY condition can also be reflected by the on/off condition of the CA or
CD leads in the interface.
Using the ETX/ ACK protocol requires that a block of text from the host be
terminated by an ETX control code. When the printer sees the ETX, it sends
an ACK to the host, signaling receipt of the block. The maximum block size
is the input buffer minus one.
One of two modes of ETX/ ACK operation can be selected using serial
interface straps A25 and A26.
With A25 IN, an immediate ACK is sent for each received ETX until the
buffer is at least 75% full. At 75% full, the buffers switch and the data is
processed.
With A26 IN, each buffer holds only one block of data, and the ACK response
won't be sent until one buffer has transferred the data for processing.
Strap A26 overrides A25 if both straps are IN.
Signals and signal levels conform to EIA RS-232C/CCrIT
V.24
standards.
0.1p<<r 4.
Printer
ln1erf1«
4-7
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