A battery is a convenient voltage source for checking the
Model 301. Connect the positive and negative ends of the battery
to a pair of positive and negative analog input pins on the analog
input connector. (Pins 14 and 1, respectively for channel 0). You
will also need a wire from one end (normally the negative) of the
battery to ground at the Model 301 to insure that the input
voltage at both input terminals is within 6.5 volts of ground. The
ground at pin 3 is provided for the purpose. This extra ground is
for common-mode requirements only, and while necessary, it is non-
critical. Remember that the Model 301 is optically isolated and
floats in comparison to the computer chassis ground. A typical D
cell should read about 1.5 volts. Reverse the wires and note the
polarity change. Connecting the input wires directly together will
cause a potential of zero volts. An open circuit will read
unpredictably. A positive overvoltage will read 5 volts. A
negative overvoltage will read -5 volts. The analog input channels
are protected against continuous overvoltage up to 60 volts.
Because of the extreme resolution possible with the Model 301
it is necessary to carefully shield your input signals from
electrical noise. Electrical noise can be radiated through the
air and picked up by wiring and/or circuitry. It can also be
introduced via the power connections. Also, air currents can
create sufficient temperature changes to cause thermal noise.
25-PIN CONNECTOR PINOUT (analog)
|
PIN 13
|
Digital Ground
|
|
|
|
|
|
PIN 25
|
Digital Out 7
|
|
PIN 12
|
Digital In 0
|
|
|
|
|
|
PIN 24
|
Digital Out 6
|
|
PIN 11
|
Digital In 1
|
|
|
|
|
|
PIN 23
|
Digital Out 5
|
|
PIN 10
|
Digital In 2
|
|
|
|
|
|
PIN 22
|
Digital Out 4
|
|
PIN 9
|
Digital In 3
|
|
|
|
|
|
PIN 21
|
Digital Out 3
|
|
PIN 8
|
Digital In 4
|
|
|
|
|
|
PIN 20
|
Digital Out 2
|
|
PIN 7
|
Digital In 5
|
|
|
|
|
|
PIN 19
|
Digital Out 1
|
|
PIN 6
|
Digital In 6
|
|
|
|
|
|
PIN 18
|
Digital Out 0
|
|
PIN 5
|
Digital In 7
|
|
|
|
|
|
PIN 17
|
Digital Ground
|
|
PIN 4
|
Digital Ground
|
|
|
|
|
|
PIN 16
|
Analog Ground
|
|
PIN 3
|
Analog Ground
|
|
|
|
|
|
PIN 15
|
CHANNEL 1+
|
|
PIN 2
|
CHANNEL 1-
|
|
|
|
|
|
PIN 14
|
CHANNEL 0+
|
|
PIN 1
|
CHANNEL 0-
|
|
|
|
|
Note: For maximum protection, any unused input terminals should be connected to ground. This is done to protect
the circuitry from static discharges which can be of extremely high voltage. Open inputs can also pick up noise.
Strain-relief is recommended for all permanent wiring on the connector. Otherwise, physical stress may cause the
failure of an electrical connection. The connector hood provided has a strain-relief clamp.
TYPICAL INPUT CONNECTIONS
back to table of contents
|
