Measurement Computing PointScan 100 Series rev.1.0 - Manual (Page 25)

PointScan/100 User’s Manual 9-12-01 Discrete / Analog Modules 6-1
Discrete / Analog Modules 6
This section documents the following modules:
PointScan/130, PointScan/109
PointScan/130
8 Discrete Inputs and 8 4-20 mA Inputs
Overview
Eight 4-20 mA inputs provide 14 bit analog measurements. Discrete inputs may be wired as all sourcing or
sinking. An input count feature uses analog input registers to accumulate the positive transitions of each
input. More information on this and other features can be found in the on-line help supplied with the IO
Toolkit program.
Number of Channels 8 analog inputs (14 bit resolution), 8 discrete inputs
Input Range 4 - 20 mA (analog), 12/24 VDC/VAC (discrete)
Analog Input Impedance 100 ohms Note: input voltage drop = 2 volts at 20 mA
Discrete Input Voltage Range 12/24 VDC/VAC
Input Current @ 24 VDC 6.7 mA
Wiring and Jumpers
Positive DC or AC voltage must be applied to an input to indicate an ON condition. All channels are
referenced to a common return or supply, which is connected to the negative side (ground) or positive side
(DC+) of the DC power source. One wire from each sourcing field input should be bussed together and
connected to terminal 17 (DC +). One wire from each sinking field input should be bussed together and
connected to terminal 18 (DC GND). Refer to the wiring diagram below. Set jumper W1 to match the wiring
configuration of the discrete inputs. A single input terminal is provided for each analog input channel. Care
must be taken to externally provide a suitable instrumentation ground for these single ended input circuits.
Current Shunts
Precision 100 ohm current shunts, beneath the hinged access door in the wiring base, pass current and
maintain loop integrity even if the module is unplugged. A spare shunt is provided and may be simply
inserted in place of any shunt that open circuits as a result of a current overload.
I/O Registers
Function IOtech Registers Modbus Registers
Analog Inputs AX0 – AX7 30001 – 30008
Discrete Inputs X0 – X7 10001 – 10008
Counter Inputs AX8 – AX15 30009 – 30016