Owner`s manual

Analog Input Module
9-5
Module Status and Diagnostics
In the event of AI Module failure, the I/O module ERR LED will be lit. The event is registered
by the CPU in the Error Logger. AI Module failure status is also visible to the user application
program.
In addition to the ERR LED, the module includes an Underflow (UDF) and Overflow (OVF)
LED for each input.
• When the UDF LED is lit, it indicates that the signal level in the corresponding input is below
the nominal range.
• When the OVF LED is lit, this indicates that the signal level in the corresponding AI is above
the nominal range.
• If both the UDF and OVF LEDs of the same channel are lit, the channel is uncalibrated.
The AI module can be diagnosed and monitored using the STS Hardware Test utility. The
Hardware Test verifies that the module is operational, presents the module configuration and
shows the actual value of each input, including overflow and underflow. It is also possible to
change the input filter setup for the duration of the Hardware test.
In the HW Test utility, it is possible to set the AI module to Freeze Mode. In this mode the
program user will get the KLV or PDV of each input in the module instead of the actual input
value. Freeze mode enables testing the inputs while the user application program is running.
AI Module Value Representation
In ± 20 mA
current inputs
Decimal Value Input Current Indication
< -32256 < -20.16 mA Underflow LED ON
-32000 -20 mA
0 0 mA
32000 +20 mA
Rated range (no LED
active)
> 32256 > +20.16 mA Overflow LED ON