User manual

Publication 1756-RM093F-EN-P - January 2010 43
Characteristics of Safety Tags, the Safety Task, and Safety Programs Chapter 5
Safety-locking the safety task once testing is completed is
recommended for SIL 2 applications. Locking the safety task enables
additional security features. You may also use FactoryTalk Security
and RSLogix 5000 routine source protection to limit access to
safety-related logic.
For more information on generating a safety task signature and
safety-locking the safety task, refer to the GuardLogix Controllers User
Manual, publication 1756-UM020
, or the Compact GuardLogix
Controllers User Manual, publication 1768-UM002
.
SIL 2 Safety Inputs
CompactBlock Guard I/O (1791-series) and ArmorBlock Guard I/O
(1732-series) safety input modules support single-channel SIL 2 safety
input circuits. Since these modules are also rated for SIL 3 operation,
mixing SIL 2 and SIL 3 circuits on the same module is allowed,
provided you follow these guidelines.
These two wiring examples show how to wire SIL 2 safety circuits to
Guard I/O safety input modules. These examples make use of
onboard test sources (T0…Tx) that are resident on all 1791 and 1732
safety input modules.
Input Wiring
Guard I/O modules group inputs in pairs to facilitate Cat 3, Cat 4, and
SIL 3 safety functions. For use in Cat 1, Cat 2, and SIL 2 safety
functions, module inputs should still be used in pairs as illustrated.
Two SIL 2 safety functions are shown wired to inputs I0 and I1 using
test sources T0 and T1, respectively.
Input Wiring in Pairs
I0 I1 T0 T1
I0 I1 T0 T1