Rockwell Automation Publication 1715-RM001A-EN-P - June 2019
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Using 1715 Hardware in a ControlLogix SIL 2 System
Chapter 4
Input modules can be configured to operate in SIL 2 energize-to-action or de-
energize-to-trip applications.
The digital output module is rated at SIL 2 as a fail-safe module. Each module
provides the following safety functions:
• Output channel signals are based on commands from the controller.
• Redundant voltage and current measurements are sent to the controller for
monitoring and diagnostics.
• Modules feature overcurrent and overvoltage channel protection.
• Diagnostic tests are executed on command from the adapter and results are
reported back to the adapter.
• On power-up or module insertion, all output channels are set to the de-
energized (fail-safe) state until command states are received from the
controller. Each channel is driven individually according to the command
state values.
• The module enters a Shutdown mode when the time between controller
communications exceeds the CRTL.
• If a module fails, then all of its channels are set to the de-energized state.
Output modules support high availability when configured for duplex operation
and using the appropriate termination assembly.
The digital output module incorporates line test functionality that can detect
and indicate 'no load' field faults. This functionality can be enabled or disabled.
The analog output module can be used in applications where the output current
is in the range 4…20 mA during normal operation including trip/action value
and where 0 mA is the fail-safe value. The analog output module is rated at SIL 2
as a fail-safe simplex module and when used in a 1oo2 configuration as a duplex
module with these features:
• Commanded values and scaling factor
The fail-safe lowest commanded value irrespective of the scaling factor is 0 mA.
The application cannot change the scaling factor; only an online update can
change the scaling factor.
The fail-safe guard is 1% (0…2 mA) and not user-configurable.
