Allen-Bradley AADvance T9110, Руководство по безопасности, Страница: 51 / 131

Rockwell Automation Publication ICSTT-RM446N-EN-P - April 2018 51
AADvance System Architectures Chapter 3
Digital Output Modules
• For de-energize to action operation one digital output module is
sufficient for SIL 3 requirements. However, for energize to action
operation, dual digital output modules are required.
• A digital output module fault must be repaired within the MTTR
which was used in the PFD calculation.
Analogue Output Modules
• The fail-safe state current of the analogue output module is less than
2mA.
• For de-energize to action operation one analogue output module is
sufficient for SIL 3 requirements. However, for energize to action
operation, dual analogue output modules are required.
• An analogue output module fault must be repaired within the MTTR
which was used in the PFD calculation.
Table 8 - Modules for SIL 3 Fail-safe I/O, Fault Tolerant Processor
Fault Tolerant I/O Architectures
A SIL 3 fault tolerant processor and I/O is achieved by dual input and output
module configurations with dual or triple processor modules. The processor
modules operate in 1oo2D under no fault conditions, degrade to 1oo1D on
the detection of the first fault in either module and fail-safe when there are
faults on both modules.
Similarly the input modules operate in 1oo2D under non faulted conditions
and 1oo1D on detection of the first fault in either module and will fail-safe
when there are faults on both modules.
Unless compensating measures are defined in the Safety Requirements
Specification (SRS) and documented in operating procedures, the application
program must be designed to shut down safety instrumented functions if a
Position Module Type
I/P A T9401/2 Digital Input Module, 24V c, 8/16 C
T9801 Digital Input TA, 16 Channel, Simplex
or
T9431/2 Analogue Input Module, 8/16 channel
+ T9831 Analogue Input TA, 16 Channel, Simplex
T9300 Base unit
CPU A & CPU B 2 x T9110 Processor Module, T9100 Base Unit
O/P A 1 x T9451 Digital Output Module, 24V dc, 8 Channel
+ T9851 Digital Output TA, 24V dc, 8 Channel, Simplex
or
1 x T9481/T9842 Analogue Output Module, 3/8 Ch, Isolated
+ T9881 Analogue Output TA, 8 Ch, Simplex