Measurement Computing PointScan 300 Series rev.1.0 - Manual (Page 17)

PointScan/300 User’s Manual 8-23-01 Discrete Input Modules 4-1
Discrete Input Modules 4
This section documents the following modules:
PointScan/321 PointScan/322 PointScan/323 PointScan/324
PointScan/325 PointScan/326 PointScan/327
8 Channel Input Modules
PointScan/300 eight channel discrete input modules incorporate one of two module base styles. These base
styles and other features are detailed below.
Standard Base
With the standard base, one terminal from each channel is connected to an internal common bus. A single
user power connection to the module allows up to eight input devices to be connected in sourcing or
sinking configurations using two wires each.
Optional Universal Wiring Base
With the optional Universal Wiring base, each discrete input has two independent screw terminals to
provide point to point isolation.
Input Isolation
All discrete inputs are optically isolated from the PointScan/300 series circuitry, regardless of the module
base style. If the optional Universal base is used, the discrete inputs will be channel to channel isolated as
well.
Sinking or Sourcing Wiring
AC inputs should be wired in a sourcing configuration as shown on the next page. All DC input modules
(except the PointScan/325) will read either DC sinking or sourcing wiring. Just reverse the power input
wires (terminals 17 and 18) to configure sinking or sourcing DC wiring.
Counter Feature
All eight channel discrete input modules have an input count accumulator feature. If this feature is enabled
(in the Remote IO Toolkit program), an analog input register will report a unipolar (unsigned) 16-bit count
value that increments on each OFF to ON transition of the corresponding input. The maximum count input
rate is 100 Hz (6000 pulses/min). These accumulations initialize at zero each time power is cycled. They
cannot be reset under software control.