Rockwell Automation 1756-SPESMNRMXT GuardLogix Controllers User Manual - Manuel (Page 16)

16 Rockwell Automation Publication 1756-UM020I-EN-P - August 2012
Chapter 1 System Overview
For information on assigning the SNN, see Managing the Safety Network
Number (SNN) on page 53 .
Safety Task Signature
The safety task signature consists of an ID number, date, and time that uniquely
identifies the safety portion of a project. This includes safety logic, data, and
configuration. The GuardLogix system uses the safety task signature to
determine the project’s integrity and to let you verify that the correct project is
downloaded to the target controller. Creating, recording, and verifying the safety
task signature is a mandatory part of the safety-application development process.
See Generate a Safety Task Signature on page 106 for more information.
Distinguishing Between
Standard and Safety
Components Slots of a GuardLogix system chassis not used by the safety function may be
populated with other ControlLogix modules that are certified to the Low
Voltage and EMC Directives. Refer to
http://ab.com/certification/ce to find the
CE certificate for the Programmable Control – ControlLogix Product Family
and determine which modules are certified.
You must create and document a clear, logical, and visible distinction between the
safety and standard portions of the application. To aid in creating this distinction,
RSLogix 5000 programming software features safety identification icons to
identify the safety task, safety programs, safety routines, and safety components.
In addition, the RSLogix 5000 software uses a safety class attribute that is visible
whenever safety task, safety programs, safety routine, safety tag, or safety
Add-On Instruction properties are displayed.
The controller does not allow writes to safety tag data from external HMI devices
or via message instructions from peer controllers. RSLogix 5000 software can
write safety tags when the GuardLogix controller is safety-unlocked, does not
have a safety task signature, and is operating without safety faults.
The ControlLogix Controllers User Manual, publication 1756-UM001 ,
provides information on using ControlLogix devices in standard (nonsafety)
applications.
HMI Devices
HMI devices can be used with GuardLogix controllers. HMI devices can access
standard tags just as with a standard controller. However, HMI devices cannot
write to safety tags; safety tags are read-only for HMI devices.