Omron CP1H CPU UNITS - PROGRAMMING 05-2007, Operation Manual

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Analog I/O (XA CPU Units)
Section 5-5
4 to 20 mA Outputs
When the resolution is set to 1/6,000, the hexadecimal values 0000 to 1770 (0
to 6,000) correspond to an analog current range of 4 to 20 mA.
When the resolution is set to 1/12,000, the hexadecimal values 0000 to 2EE0
(0 to 12,000) correspond to an analog current range of 4 to 20 mA. The entire
output range is 3.2 to 20.8 mA.
The following diagram shows conversion values for 1/6,000 resolution.
Averaging Function for
Analog Inputs The averaging function stores 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.
Use the CX-Programmer to set the averaging function in the PLC Setup. The
averaging function can be set independently for each input or output.
Open-circuit Detection
Function for Analog
Inputs The open-circuit detection function is activated when the input range is set to
1 to 5 V and the voltage 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 detec-
tion 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 converting 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.
Auxiliary Area bits A434.00 to A434.03 are allocated as open-circuit detection
flags.
4 mA
20 mA
20.8 mA
3.2 mA
189C
(6300)
1770
(6000)
0 mA
7FFF
FED4
(
−
300)
8000
Conversion Data
Hexadecimal (Decimal)
Bit Function
A434.00 Analog Input 0 Open-circuit Error Flag 0: No error
1: Open-circuit error detected
A434.01 Analog Input 1 Open-circuit Error Flag
A434.02 Analog Input 2 Open-circuit Error Flag
A434.03 Analog Input 3 Open-circuit Error Flag