Rockwell Automation 1791DS-IBxxxx Guard I/O DeviceNet Safety Modules - Manual (Page 26)

26 Rockwell Automation Publication 1791DS-UM001J-EN-P - May 2013
Chapter 2 Understand the Operation of Safety Functions
The module is designed for use in applications where the safety state is the off
state.
Self-diagnostic Functions Self-diagnostics are performed when the power is turned on and periodically
during operation. If a fatal internal module error occurs, the red module status
(MS) indicator is illuminated, and the safety outputs and input data and status to
the network turn off.
Configuration Lock After configuration data has been downloaded and verified, the configuration
data within the module can be protected by using RSNetWorx for DeviceNet
software.
For GuardLogix systems, this status indicator is not used. Reference information
about safety signatures in the GuardLogix Controller Systems Safety Reference
Manual, publication
1756-RM093 or the GuardLogix 5570 Controller System
Safety Reference Manual, publication 1756-RM099 .
I/O Status Data In addition to I/O data, the module provides status data for monitoring the I/O
circuits. The status data includes the following data, which can be read by the
controllers. Note that 1 = ON/Normal and 0 = OFF/Fault/Alarm.
• Individual Point Input Status
• Combined Input Status
• Individual Point Output Status
• Combined Output Status
• Individual Test Output Status
• Individual Output Readback (actual ON/OFF state of the outputs)
Status data indicates whether each safety input, safety output, or test output is
normal (normal status: ON, faulted status: OFF). For fatal errors,
communication connections may be broken, so the status data cannot be read.
Status bits are OFF in the GuardLogix data table when the connection is lost.
Combined status is provided by an AND of the status of all safety inputs or all
safety outputs. When all inputs or outputs are normal the respective combined
status is ON. When one or more of them has an error, the respective combined
status is OFF. This is known as the combined safety input status or combined-
safety output status.
Safety Inputs Read this section for information about safety inputs and their associated test
outputs. A safety input may be used with test outputs. Safety inputs are used to
monitor safety input devices.