22
The Advanced
®
Osmometer Model 3320 Service Manual
Serial (RS-232) Port Interface: An RS-232
line driver/receiver provides the microproces-
sor with a serial port interface that supports
both hardware and software handshaking.
The DB-9 RS-232 port conforms to the DTE
RS-232C standard and has the following pin
assignments:
Signal Pin Direction
Carrier Detect 1 to 3320
Receive Data 2 to 3320
Transmit Data 3 from 3320
Data Terminal Ready 4 from 3320
Signal Ground 5 common
Data Set Ready 6 to 3320
Request to Send 7 from 3320
Clear to Send 8 to 3320
Note that the instrument is only designed to
support unidirectional communication with an
external device. At this time, there is no pro-
tocol for bidirectional communication.
For a sample RS-232 Port Setup, please see
the RS-232 Supplemental Information in the
Appendix at the end of the user’s guide.
Note: This instrument requires the use of a
null modem RS-232C cable. There are
several variations on null modem
cables. Advanced Instruments recom-
mends that the RS-232C cable be pur-
chased directly from our factory.
Barcode Port: A D-type, 15-pin barcode port
is provided in the back of the 3320 for con-
necting and providing power to such a device.
For proper operation, the barcode port
requires a 1200 bps, RS-232 signal providing
asynchronous serial data containing 1 start
bit, 8 data bits, 1 stop bit, and no parity.
A suitable barcode scanner is available from
Advanced Instruments. To interface with the
3320, the barcode scanner must be pro-
grammed as follows, referring to the scanner
users guide.
1200 bps
CR suffix
disable beep after good decode
triggerless trigger mode (optional)
Secondary Cooling Fan: A 12VDC second-
ary exhaust fan is mounted to the rear panel
and used for providing cool air flow over the
power supply and control board set. This fan
remains on as long as power is on for the
instrument. The fan is connected to the
+15VDC output from the power supply
through a power resistor, which drops the
voltage to +12VDC.
+5V DC 1 to reader
receive data 10 from reader
gnd/earth 9 common
Signal Pin Direction
Barcode Port Connections
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