Measurement Computing PointScan 200 Series rev.1.0 - Manual (Page 25)

PointScan/200 User’s Manual 9-25-01 Analog Output Modules 6-1
Analog Input Modules 6
Note: It is not necessary to recalibrate analog I/O if a logic module is replaced.
Analog logic modules may be hot swapped and will not require recalibration. User calibration data is stored
in system memory outside of the analog module. Factory calibration data is stored in memory in the plug-in
logic module. Since all logic modules are calibrated to the same factory standards, recalibration is not
necessary if logic modules are moved or replaced.
PointScan/201
8 Channel 4-20 mA Analog Inputs
Overview
Eight 4-20 mA inputs provide 16 bit high resolution analog measurements. Each input circuit in this
module provides a field selectable choice of providing DC power (for loop powered transmitters) or
accepting a ground return (from internally powered instruments). More information can be found in the on-
line help supplied with the IO Toolkit.
Number of Channels 8 (16 bit resolution)
Input Range 4 - 20 mA
Input Impedance 100 ohms Note: input voltage drop = 2 volts at 20 mA
Wiring
Two terminals are provided for each input channel. Either DC power or ground may be provided for each
input device by setting a jumper inside the base. (Access these jumpers by unplugging the module and then
opening the hinged door in the wiring base.) Refer to the diagram below. Please be sure to provide a
suitable instrumentation ground to avoid measurement errors due to ground loops.
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 socketed 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 Bipolar values: -32768
Æ 32767