supporting Sequence of Events

Publication 1732E-UM002A-EN-P - March 2010
Module Features 45
Input Diagnostics
As with other modules with diagnostics, the input connector’s Sensor Source
Voltage (SSV), on Pin 1 of the input connectors, is protected from short
circuits to ground as well as open wire conditions due to a missing sensor or to
a cable disconnection.
Short Circuit Protection
Each connector with inputs is protected against short circuits to ground. The
circuit automatically resets each connector individually and the SSV energizes
once the short circuit is removed.
When a short circuit condition is detected, the module issues a diagnostic for a
short circuit in the module’s input tag and solid red input LEDs are illuminated
for the inputs associated with that connector. For more information on
interpreting Status Indicators, see page 69
.
Short circuit detection cannot be disabled.
Open Wire Detection
Open Wire Detection can be used to monitor each input connector for cable
disconnection conditions.
• If Open Wire Detection is enabled, the module monitors the enabled
input connectors for cable disconnections. If an open wire condition is
detected, the module issues a diagnostic for an open wire in the
module’s input tag and blinks the red diagnostic LEDs for the inputs
associated with that connector. For more information on interpreting
Status Indicators indicators, see page 69
.
• If Open Wire Detection is disabled, the module will not signal a fault for
the disabled input connectors.
Disabling Open Wire Detection on unused inputs prevents the module from
signaling a fault even though nothing is connected to it. This feature is set on
an input connector basis and is disabled for all inputs by default.