15 Troubleshooting
15.1 Analog
Inputs
Problem
Action
20mA inputs always read 0.
Check transmitter power.
Reading is at or near 0 for
all input signals.
Check if the input transient suppressers are
damaged.
20mA readings are not
accurate.
Check for a damaged 250
Ω
current sense
resistor.
Inputs are 0-20mA, not 4-20mA.
Reading is constant.
Check that the analog input is not forced.
15.2 Analog
Outputs
Problem
Action
Outputs are always 0mA
Check the 24V power.
The full-scale output is less
than 20mA.
Check the 24V power.
Check that the load resistance is within
specification.
Output is constant and
should be changing.
Check that the analog outputs are not forced.
15.3 Digital
Inputs
Problem
Action
Input LED does not come
on when input signal is
applied.
Check the input signal at the termination block. It
should be at least 50% of the digital input range.
If this is a DC input, check the polarity of the
signal.
Input is on when no signal is
applied. The LED is off.
Check that the digital inputs are not forced on.
Input is off when a signal is
applied. The LED is on.
Check that the digital inputs are not forced off.
Input is on when no signal is
applied. The LED is on.
Check that the digital output at that point is off.
The LED is dim.
This is normal operation when the controller is in
low power mode or sleep mode, or when the
LEDs are turned off.
Check the controller digital I/Os are in the register
assignment.
SCADAPack 350 Hardware Manual
February 14, 2007
55
