9-5
9 Using Expansion Units and Expansion I/O Units
CP1E CPU Unit Hardware User’s Manual(W479)
9-1 Analog Input Units
9
9-1-3 Specifications
z Averaging Function
For analog inputs, the averaging function operates when the averaging bit is set to 1. The averaging
function outputs the average (a moving average) of the last eight input values as the converted
value.
Use this function to smooth inputs that vary at a short interval.
z Open-circuit Detection
The open-circuit detection function is activated when the input range is set to 1 to 5 V and the volt-
age drops below 0.8 V, or when the input range is set to 4 to 20 mA and the current drops below
3.2 mA.
When the open-circuit detection function is activated, the converted data will be set to 8,000.
The time for enabling or clearing the open-circuit detection function is the same as the time for con-
verting the data. If the input returns to the convertible range, the open-circuit detection is cleared
automatically and the output returns to the normal range.
0 to 20 mA Inputs
Currents in the 0 to 20 mA range correspond to
hexadecimal values 0000 to 1770 (0 to 6,000). The
range of data that can be converted is FED4 to
189C hex (-300 to 6,300). A negative current is
expressed as a two’s complement.
4 to 20 mA Inputs
Currents in the 4 to 20 mA range correspond to
hexadecimal values 0000 to 1770 (0 to 6,000). The
range of data that can be converted is FED4 to
189C hex (-300 to 6,300). Current in the range of
3.2 to 4 mA is expressed as a two’s complement.
If an input is below the range (i.e., less than 3.2 mA),
the open-circuit detection function is activated and
the data becomes 8,000.
0 mA 20 mA
21 mA
−1 mA
Converted data
Hexadecimal (Decimal)
189C (6300)
1770 (6000)
0000 (0)
FED4 (−300)
Converted data
Hexadecimal (Decimal)
189C (6300)
1770 (6000)
0000 (0)
FED4 (−300)
4 mA 20 mA
20.8 mA
3.2 mA
0 mA
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