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Chapter 15 RS-232 And RS-422 Serial Interfaces
The printer interface uses a first-in/first-out buffer. The asynchronous
interface accepts data as it is provided by the host. The length of the data
cable from the host computer to the printer must not exceed 50 feet (15
meters) for RS-232 or 4000 feet (1220 meters) for RS-422. (A copper
conductor, twisted-pair telephone cable with a shunt capacitance of 16 pF/
foot [52.5 pF/meter] terminated in a 100 ohm resistive load must be used for
the RS-422.)
RS-232 And RS-422 Serial Interface Signals
The RS-232/RS-422 connector mounted on the printer is a 25-pin DB-25S
type. The mating connector is a DB-25P. RS-232 and RS-422 compatible
serial interface signals are defined as follows:
RS-232
Transmitted Data (TD). Serial data stream from the printer for transmitting
status and control information to the host. Subject to protocol selection.
Received Data (RD). Serial data stream to the printer.
Request To Send (RTS). Control signal from the printer. Subject to
configuration.
Clear To Send (CTS). Status signal to the printer indicating the host is ready
to receive data/status signals from the printer.
Data Set Ready (DSR). Status signal to the printer indicating the host is in a
ready condition.
Table 20. RS-232 Serial Interface Connector Pin Assignments
Input Signals Output Signals Miscellaneous
Signal Pin Signal Pin Signal Pin
Receive Data (RD) 3 Transmit Data (TD) 2 Chassis Ground 1
Clear To Send (CTS) 5 Request To Send (RTS) 4 Signal Ground 7
Data Set Ready (DSR) 6 Data Terminal Ready (DTR) 20
Data Carrier Detect (DCD) 8
Table 21. RS-422 Serial Interface Connector Pin Assignments
Input Signals Output Signals Miscellaneous
Signal Pin Signal Pin Signal Pin
- Receive Data (-RD) 15 - Transmit Data (-TD) 19 Chassis Ground 1
+ Receive Data (+RD) 17 + Transmit Data (+TD) 25 Signal Ground 7