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

Appendix AResponse Times in ControlLogixThe following calculation methods provide the user with theworst-case reaction times for a given change in input or faultcondition and the corresponding output action.Digital ModulesLocal Chassis ConfigurationFigure A.1 shows an example system where the following occurs:• input data changes on the digital input module• the data is transmitted to the controller• the controller runs its program scan and reacts to the datachange, including sending new data to the output module• the output module behavior changes based on the new datareceived from the controllerFigure A.1Digital InputModuleControllerDigital OutputModuleUse the following formula to determine worst-case reaction time:Worst-Case Reaction Time = Input Module Filter Setting (1) + Input Module Hardware Delay (2)+ Input Module RPI (1) + Controller Program Scan (3)+ Output Module Hardware Delay (2)(1)This setting is user-defined. For more information, see the ControlLogix Digital I/O Modules user manual,publication 1756-UM058.(2) Hardware delay is module-dependent. Specific hardware delay times are listed in the installation instructions for eachcatalog number. For a complete list of installation instructions, see Table 1.1 on page 1-6.(3)This figure is calculated by adding instruction execution times. For more information on instruction execution times inRSLogix 5000, see the Logix5000 Controllers Execution Time and Memory Use Reference, publication 1756-RM087.1 Publication 1756-RM001B-EN-P - October 2003