1756-RM001B-EN-P, Using ControlLogix in SIL2 ... - Tuv-fs.com

1-16 SIL PolicyProgram Watchdog Time inControlLogix SystemThe program watchdog (also known as the software watchdog) timeis a user-defined time that is set in the controller attributes menu ofthe RSLogix 5000 software. See the ControlLogix System User Manual,publication number 1756-UM001 for more information. Thepublication is available from Rockwell Automation.The program watchdog time is the maximum permissible timeallowed for a RUN cycle (cycle time). If the cycle time exceeds theprogram watchdog time, a major fault occurs on the controller. Usersmust monitor the watchdog and program the system outputs totransition to the safe state (typically the OFF state) in the event of amajor fault occurring on the controller. For more information onfaults, see Chapter 7, Faults in the ControlLogix System.The program watchdog time must be ≥ 10 ms and must be < 50% ofthe safety time required for a ControlLogix system. The safety time isthe maximum amount of time in which the process tolerates a wrongsignal.Contact Information WhenDevice Failure OccursWhen users experience a failure with any SIL2-certified ControlLogixdevice, they should contact their local Rockwell Automation salesoffice. With this contact, the user can:• return the device to Rockwell Automation so the failure isappropriately logged for the catalog number affected and arecord made of the failure.• request a failure analysis (if necessary) to determine the cause ofthe failure, if possible.Publication 1756-RM001B-EN-P - October 2003