Safety Considerations Guide, Tricon v9.0 - Tuv-fs.com

Sample Safety-Shutdown Programs 65Defining Function Blocks▼To create a user-defined function block for a safety-critical module:1 Copy the example EX02_CRITICAL_IO in the ExTUV.pt2 sample projectprovided with the TriStation 1131 Developer’s Workbench.2 Edit the lines following the comment “Include all safety-critical I/O moduleshere.”Each line calls the safety-critical I/O (SCIO) function block for one safetycriticalI/O module.Example**************************************************************)(* Include here all safety-critical I/O modules: *)SCIO( CHASSIS:=1,SLOT:=1,APP:=DE_ENERGIZED,RELAY_OK:=FALSE ): (*DI*)SCIO( CHASSIS:=1,SLOT:=2,APP:=RELAY, RELAY_OK:=RELAY1_OK ); (*DO*)SCIO( CHASSIS:=1,SLOT:=3,APP:=RELAY, RELAY_OK:=RELAY1_OK ); (*DO*)(* ( CHASSIS:=1,SLOT:=4,NOT CRITICAL) *) (*RO*)(3 (Enter the correct CHASSIS number, SLOT number, APP (application), andRELAY_OK parameters for the safety-critical I/O module.Application Type(App)RELAY(de-energized to tripwith relay)RELAY(de-energized to tripwith relay)DE-ENERGIZED(de-energized to tripwith no relay)Relay_OKParameterTrueFalse—DescriptionA voter fault degrades the mode to dual. Therelay provides a third channel for shutdownso that if an output voter fails, there remaintwo independent channels (the relay andother output voter channel) that can deenergizethe output.A voter fault degrades the mode to single. Anon-voter fault degrades the mode to dual.Chapter 4Application Development