Advanced Instruments 3900, Service Manual

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The fluid level probes are interfaced to a
peripheral interface adapter through discrete
logic. The peripheral interface adapter
interfaces with the microprocessor. There are
three LEDs located on the motor control
board which indicate the fluid level status.
• Yellow on indicates fluid level low.
• Yellow/ green on indicates fluid level half.
• Red/green/ yellow on indicates fluid level
full.
The status of the fluid level can also be
checked by using the “reservoir status”
function in the setup menu.
Serial Communication Port
Serial RS-232 Port Interface:
An Asynchronous Communications Interface
Adapter and RS-232 line drivers/receivers
provide the microprocessor with a serial port
interface that supports both hardware and
software handshaking.
The RS-232 port has the following pin
assignments:
Signal DB-9 Pin
Carrier Detect 1
Receive Data 2
Transmit Data 3
Data Terminal Ready 4
Signal Ground 5
Data Set Ready 6
Request to Send 7
Clear to Send 8
Head Rotation System
The disk sensor circuit controls the position
of the sample head at the cassette tube
retrieval/placement position. The controlling
system consists of an optical switch
(adjustable) and a slotted disk. The optical
switch is interfaced to the microprocessor
through a peripheral interface adapter.
The head rotation travel is controlled by two
mechanical limit switches; one is located on the
right side and one on the left side. The limit
switches are interfaced to the microprocessor
through a peripheral interface adapter.
Barcode Port:
A D-type, 15-pin barcode port is provided in
the back of the instrument for connecting and
providing power to such a device. For proper
operation, the barcode port requires a 1200
bps TTL 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
instrument, the barcode scanner must be
programmed as follows, referring to the
scanner user’s guide.
1200 bps
CR suffix
disable beep after good decode
triggerless trigger mode (optional)
The Advanced ® Model 3900 Service Manual
+5V DC 1 to reader
receive data 10 from reader
gnd/earth 9 common
Signal Pin Direction
Barcode Port Connections