Serial Port; Serial Port Features; Serial Port Pin-Out; Table 14 Serial Bit Rates - Ithaca 150 Programmer's Manual

Programmer's Guide

Serial Port

Serial Port Features

The serial port features are as follows:
Baud rates
Bit patterns
Flow control

Table 14 Serial bit rates

It should be noted that the 7-bit, no parity is in fact an 8-bit format. The implementation of the
hardware UART in the Intel 8051 family will not allow a true 7-bit, no parity format. If the host
provides a true 7-bit, no parity format, it must be configured with two stop bits.
The Series 150 Printer has a 64-character high-speed buffer before the main system buffer. This
high-speed buffer allows the printer to operate at high serial data rates while printing. Because
no data is evaluated in this buffer, the printer will have a delayed response to inquire requests
and [CR]'s in one-line operation. This has a significant effect on one-line mode operation.

Serial Port Pin-out

Not connected
Used in printer
Output to host
Ready and/or flow
control signal to
host
Disable printer
control from host
Ready and/or flow
control signal to
host
Flow control from
host
*Strapable 12 V or
DTR

Table 15 Serial port pin-outs

Because both the host and the printer are DTE's (Data Terminal Equipment), they use the same
serial port pin-outs. If the cable that is used to connect the host to the printer is a pin-to-pin
interconnect, it will not work. For this reason, a null modem or turn-around cable must be used to
interconnect the host and the printer.
Signal levels
The serial interface meets EIA RS-232 requirements.
Logic 1
Logic 0
12/14/99
PcOS Series 150
300, 600, 1200, 2400, 4800, 9600, 19.2K
8-bit, no parity; 8-bit odd; 8-bit even; 7-bit no parity; 7-bit odd; 7-bit even
DTR and XON/XOFF
Input Pin 1 DCD
Input Pin 2 RX
Output Pin 3 TX
Output Pin 4 DTR
Pin 5 GND
Input Pin 6 DSR
Output Pin 7 RTS
Input Pin 8 CTS
Output Pin 9 SSD
-15 V to -3 V: mark = off
+3 V to +15 V: space = on
Rev G
Communications
Data carrier Not used
detect
Receive data Commands/data to print
Transmit data Return data
Data terminal Printer ready to receive data
ready (follows buffer)
Signal ground
Data set ready Not used in standard printer
(configurable)
Request to Printer ready to receive data
send (follows buffer)
Clear to send Not used in standard printer
(configurable)
Secondary Not used in standard printer
data (provides power to peripheral)
Serial Port
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