Emerson PAC8000 I/O Modules interface to safety system field wiring via Field Terminals. The IO Modules and
the Field Terminals mount on carriers that provide mechanical support, but also connect the internal communication
bus and power supply connections to the Modules.
The Emerson PAC8000 I/O Modules are certified for use in safety-related applications up to and including SIL 2.
The SafetyNet System achieves this certification with a 1oo1D architecture. The SafetyNet IO Modules have been designed
specifically for safety-related applications and are certified on the basis of the excellence of their design. The
certification does not depend on “proven in use” data.
The IO Modules perform comprehensive internal diagnostic tests as an essential part of ensuring that the IO can carry
out the required safety function. If the SafetyNet IO Module’s internal diagnostics detect a fault that would prevent
the SafetyNet System from carrying out its safety function,then it will initiate a controlled shutdown. A controlled
shutdown has two objectives – firstly, to ensure that the IO Module enters its failsafe mode; and secondly, to record
sufficient data to allow the reason for the shutdown to be determined. If a SafetyNet Module enters a controlled shutdown,
then all IO channels are deactivated: input channels are not scanned; and output channels are de-energized.
