User manual

Publication 1756-RM093F-EN-P - January 2010 45
Characteristics of Safety Tags, the Safety Task, and Safety Programs Chapter 5
SIL 2 Safety Control in Standard Tasks (1756 GuardLogix
Controllers Only)
Because of the quality and amount of diagnostics built into the 1756
ControlLogix series of controllers, you can perform SIL 2 safety
functions from within standard tasks. This is also true for 1756
GuardLogix controllers.
To perform SIL 2 safety control within a GuardLogix standard task,
you must abide by requirements defined in the Using ControlLogix in
SIL 2 Applications Safety Reference Manual, publication 1756-RM001
.
EN50156 Compliance With 1756 ControlLogix SIL 2 Safety Inputs
in Dual-channel Configurations with 1756 GuardLogix Controllers
Dual-channel configuration is required for compliance in certain
safety-related applications, including burner-related safety functions.
These examples provide guidelines for satisfying EN50156 SIL 2
dual-channel requirements.
SIL 2 Dual-channel Inputs (Standard Side of 1756 GuardLogix Controllers)
You must implement clear and easily-identifiable separation between
both input channels and adhere to all existing SIL 2 requirements as
defined in Using ControlLogix in SIL 2 Applications, publication
1756-RM001
.
IMPORTANT
You may not use the standard task in a 1768 Compact
GuardLogix controller for SIL-2 safety applications.
Channel A Channel B
Ch0+ Ch0+
Ch0- Ch0-
Voltage
Transmitter A
Voltage
Transmitter B
+
+
-
-