GFK-1504N
Chapter 10 Analog Input Modules
10-15
10
IC200ALG240
Analog Input Module, 16 Bit Voltage/Current, 1500 V AC Isolation, 8 Channels
Configuring Scaling
The module converts electrical signals (either current or voltage, as configured)
into digital output values for the CPU or NIU. By default, the module converts
this data from 1 millivolt or 1 microamp “internal units” for convenience in
scaling and comparing to actual meter measurements.
The module’s default scaling can be changed to tailor the data for a specific
application. Typically, engineering units represent millivolts or microamps. But
they may also represent physical units such as degrees or centimeters per
second. When reconfiguring scaling, it is important to be sure that the chosen
Engineering Units values would not result in Overrange or Underrange output
levels.
The scaling for each channel can be configured independently. Scaling is
configured by selecting corresponding low and high engineering units values
and low and high internal values (counts) for two points.
During operation, the module will use the straight line defined by these two pairs
of configured scaling values to convert internal values to current or voltage
signal levels that represent appropriate engineering units.
Scaling Values for 1mV or 1
µ
A Engineering Units
For many applications, the engineering units are either millivolts or microAmps.
These units are easy to scale. Refer to the following table for scaling values that
are appropriate for the channel’s configured range.
Examples
Input
Range
Enter this engineering
units value
Span Units
(microAmps)
4 mA to 20 mA
4 mA
20 mA
Low
+4,000
High
+20,000
Low
+4,000
High
+20,000
-10 volts to +10 volts
0 volts
+10 volts
Low
0
High
+10,000
Low
+4,000
High
+20,000
0 mA to 20 mA
0 mA
20 mA
Low
0
High
+20,000
Low
0
High
+20,000
-10 volts to +10 volts
-5 volts
+10 volts
Low
-5,000
High
+10,000
Low
-5,000
High
+10,000
