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

6-20 ControlLogix I/O ModulesUsing Analog OutputModulesThe 1756-OF8 ControlLogix analog output module is certified for useSIL2 applications.General Considerations when using Any ControlLogix AnalogOutput ModuleThere are a number of general application considerations that youmust follow when applying the analog output modules in a SIL2application:• Proof Tests - Periodically (for example, once every severalyears) a System Validation test must be performed. Manually, orautomatically, test outputs to make sure that all outputs areoperational. Channel data should be varied over the fulloperating range to make sure that the corresponding field signallevels vary accordingly. For additional information on ProofTests, see page 1-5 and Figure 9.1 on page 9-5.• Calibrate Outputs Periodically, As Necessary: ControlLogixI/O modules ship from the factory with a highly accurate levelof calibration. However, because each application is different,users are responsible for making sure their ControlLogix I/Omodules are properly calibrated for their specific application.Users can employ tests in application program logic todetermine when a module requires recalibration. For example,to determine whether an output module needs to berecalibrated, a user can determine a tolerance band of accuracyfor a specific application. The user can then measure outputvalues on multiple channels and compare those values toacceptable values within the tolerance band. Based on thedifferences in the comparison, the user could then determinewhether recalibration is necessary.Calibration (and subsequent recalibration) is not a safety issue.However, we recommend that each analog output be calibratedat least every 3 years to verify the accuracy of the input signaland avoid nuisance application shutdowns.Publication 1756-RM001B-EN-P - October 2003