Section 5: Interface Specifications
XL400/410e Operator’s Manual
Page 5-5
5.4 RS232C SERIAL INTERFACE (CONT’D)
Cable Requirements
Data Streams
Once the flow control method has been chosen for the RS232C interface, the data stream must
be sent in a specific manner. The STX and ETX control characters must frame the data stream.
<STX><ESC>A . . Job#1 . . <ESC>Z<ETX><STX><ESC>A . . Job#n . . <ESC>Z<ETX>
Note:
All characters, including STX, ESC and ETX, are in ASCII.
X-On/X-Off Flow Control
X-On/X-Off flow control must be used whenever hardware (Ready/Busy) flow control is not
available or desirable. Instead of a voltage going high/low at pin 20, control characters
representing “Printer Ready” (X-On =11 hexadecimal) or “Printer Busy” (X-Off = 13 hexadecimal)
are transmitted by the printer on pin 2 (Transmit Data) to the host. In order for this method of flow
control to function correctly, the host must be capable of supporting it. X-On/X-Off operates in a
manner similar to the function of pin 20 (DTR) as previously explained. When the printer goes on-
line, an X-On is sent out. In the Single Job Buffer mode, when the printer receives a viable job, it
transmits an X-Off and begins printing. When done printing, it transmits an X-On. In the Multi Job
Buffer mode, the printer sends an X-Off when the “Buffer Near Full” level is reached, and sends
a X-On when the data level of the buffer drops below the “Buffer Available” mark. When the
printer is taken off-line manually, it transmits an X-Off indicating it cannot accept data. When it is
placed back on-line manually, it sends an X-On, indicating it is again ready to receive data. If an
error occurs during printing (paper out, ribbon out), the printer sends nothing in the Single Job
Buffer mode since the last character transmitted was an X-Off. When the error is cleared and the
printer resumes printing, no X-On is sent until the current job is completed and the printer is
again ready to receive the next job. If it is in the Multi Job Buffer mode, it sends an X-Off as soon
as an error condition is detected. When the error is cleared and the printer is placed back on-line,
it transmits an X-On indicating it is again ready to accept data.
Upon power up if no error conditions are present, the printer will continually send X-On
characters at five millisecond intervals until it receives a transmission from the host.
Host
Interconnection
Printer
FG
1 FG (Frame Ground)
TD
3 RD (Receive Data)
4 RTS (Request To Send)
5 CTS (Clear To Send)
6 DSR (Data Set Ready)
*
20 DTR (Data Terminal Ready)
SG
7 SG (Signal Ground)