Service manual

Unit 2: Interface Specifications
D508/D512 Service Manual Page 2-11
Pin Assignments
RS-232C INTERFACE SIGNALS
Cable Requirements
Pin Direction Signal Definition
1 Reference FG (Frame Ground)
2 To Host TD (Transmit Data) -Data from the printer to the host computer. Sends X-On/X-Off
characters or status data (Bi-Directional protocols).
3 To Printer RD (Receive Data) -Data to the printer from the host computer.
4 To Host RTS (Request to Send) -Used with Ready/Busy flow control to indicate an error
condition. RTS is high and remains high unless the print head is open (in this case,
RTS would return to the high state after the print head is closed and the printer is
placed back on-line) or an error condition occurs during printing (e.g. Time Out
error, label out).
5 To Printer CTS (Clear to Send) -When this line is high, the printer assumes that data is ready
to be transmitted. The printer will not receive data when this line is low. If this line is
not being used, it should be tied high (to pin 4).
6 To Printer DSR (Data Set Ready) -When this line is high, the printer will be ready to receive
data. This line must be high before data is transmitted. If this line is not being used,
it should be tied high (to pin 20).
7 Reference SG (Signal Ground)
20 To Host DTR (Data Terminal Ready) -This signal applies to Ready/Busy flow control. The
printer is ready to receive data when this pin is high. It goes low when the printer is
off-line, either manually or due to an error condition, and while printing in the Sin-
gle Job Buffer mode. It will also go low when the data in the buffer reaches the Buf-
fer Near Full level.
Pin 1
Pin 14Pin 25
Pin 13