Specifications

I
2
C Input/Output Boards, Continued
The I
2
C AIO board makes available 8 Analog Outputs (AOs), 8 Analog
Inputs (AIs), and 2 Digital Inputs (DIs).
Analog Input/Output
Board
Figure 2-9: I
2
C Analog Input/Output Board
There are eight AO circuits available on the AIO board. The AO is able to
output currents from 0 to 25mA, although a 4 to 20mA range can be
selected in software. The range above 20mA is used to meet Namur
compliant out-of-range fault readings.
Analog Outputs
Two pins are used for each AO. One pin is a common ground. The other
pin is the AO current output pin. Each AO current output pin has
protection against high overvoltage using diode circuitry. In addition,
there is 400V isolation between the AO on the connector and the rest of
the I/O board.
AOs can be modified for voltage output by adding a resistor across the
AO terminal. Value of the resistor is dependant on the desired voltage
range, subject to Ohm's law (V=IR). Accuracy of the output is dependant
on the tolerance of the resistor. The maximum supported voltage output
is 23V, corresponding to approximately a maximum 920 ohm resistor.
A5E31405710001 2-13