Safety Considerations Guide for Trident v2 Systems - TUV ...

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46 Chapter 4 Application Development Development Guidelines To avoid corruption of project files while developing an application (also known as a control program), you should: • Use a dedicated PC that is not connected to a network. • Use a PC with ECC memory, if possible. • Use, according to the vendor’s instructions, a regularly-updated, always-on virus scanner. • Use system utilities such as Checkdisk and vendor diagnostics to periodically determine the health of the PC. • Use dependable media, such as a CD-ROM instead of a floppy disk. • Not use a system prone to crashing. • Not use battery power if using a notebook computer. • Not copy a project file while it is open in the TriStation 1131 software. • Not e-mail project files. • Verify proper installation of the TriStation 1131 software using TriStation Install Check. You should run the TriStation Install Check program to verify that the TriStation 1131 software is correctly installed on your PC and that no associated files are corrupted. This is especially helpful if applications besides the TriStation 1131 software reside on your PC. See the TriStation 1131 Developer’s Guide for instructions on using the TriStation Install Check program. Triconex Product Alert Notices (PANs) Product Alert Notices document conditions that may affect the safety of your application. It is essential that you read all current PANs before starting application development, and that you keep up-to-date with any newly released PANs. All PANs can be found on the Invensys Global Customer Support (GCS) Center website, or contact the Invensys Global Customer Support (GCS) Center for assistance (see page viii for contact information). Safety and Control Attributes Each element and tagname in the TriStation 1131 application has a safety attribute, and a control attribute. When the safety attribute is set, the TriStation 1131 software provides extra verification. If you are developing a safety application, you should set the safety attribute. VAR_IN_OUT Variables You should not use the VAR_IN_OUT variable in a safety application. Safety standards (such as IEC 61508) recommend limiting the use of pointers in safety applications; VAR_IN_OUT is used as a pointer in the TriStation 1131 application. To automatically check for the use of VAR_IN_OUT in your safety application, set the safety attribute (as described above). Safety Considerations Guide for Trident v2 Systems
Array Index Errors Infinite Loops Development Guidelines 47 If an array index error is detected during runtime, the default behavior is to trap. This results in the Trident controller going to the safe state, with all outputs de-energized. If your application requires some other behavior, you can use a CHK_ERR function block to detect the error, and a CLR_ERR function block to clear the error and prevent a trap. Note If an array index is too small or too large, the array operation is performed on the last element of the array. Array bounds checking is always turned on—there is no means to disable the array index checking. See the TriStation 1131 Libraries Reference for more information about the CHK_ERR and CLR_ERR function blocks. If the actual scan time exceeds the maximum allowable scan time for the Trident controller, the main processors will reset, causing the Trident controller to go to the safe state, with all outputs de-energized. The maximum allowable scan time for the Trident is 450 milliseconds. Although it is not possible to program an endless loop with TriStation 1131 software, it is possible to create a loop with a very long time, enough to increase the actual scan time beyond the controller’s maximum allowable scan time. See Setting Scan Time on page 49 for more information about actual and maximum scan times. Safety Considerations Guide for Trident v2 Systems
Page 1 and 2:
Trident v2 Systems Safety Considera
Page 3 and 4:
Contents Preface vii Summary of Sec
Page 5 and 6: Contents v Partitioned Processes. .
Page 7 and 8: Preface This guide provides informa
Page 9 and 10: • All other requests are handled
Page 11 and 12: 1 Safety Concepts Overview 2 Hazard
Page 13 and 14: Protection Layers Methods that prov
Page 15 and 16: Hazard and Risk Analysis Hazard and
Page 17 and 18: Sample SIL Calculation Hazard and R
Page 19 and 20: Safety Life Cycle Model Hazard and
Page 21 and 22: Hazard and Risk Analysis 11 • Eac
Page 23 and 24: CAN/CSA-C22.2 No. 61010-1-04 Safety
Page 25 and 26: 2 Application Guidelines Overview 1
Page 27 and 28: General Guidelines This section des
Page 29 and 30: General Guidelines 19 Safety Measur
Page 31 and 32: Emergency Shutdown Systems The safe
Page 33 and 34: Safety-Shutdown Guidelines for Tric
Page 35 and 36: Guidelines for Triconex Controllers
Page 43 and 44: 3 Fault Management Overview 34 Syst
Page 45 and 46: System Diagnostics System Diagnosti
Page 47 and 48: Operating Modes Each input or outpu
Page 49 and 50: Analog Output (AO) Modules Module D
Page 51 and 52: Calculation for Diagnostic Fault Re
Page 53 and 54: External Communication Module Diagn
Page 55: 4 Application Development Developme
Page 59 and 60: Setting Scan Time 49 application. T
Page 61 and 62: Sample Safety-Shutdown Programs Sam
Page 63 and 64: Sample Safety-Shutdown Programs 53
Page 65 and 66: When Some I/O Modules Are Safety-Cr
Page 67 and 68: Sample Safety-Shutdown Programs 57
Page 69 and 70: Partitioned Processes Sample Safety
Page 71 and 72: Alarm Usage Alarm Usage 61 To imple
Page 73 and 74: A Triconex Peer-to-Peer Communicati
Page 75 and 76: Data Transfer Time Data Transfer Ti
Page 77 and 78: Data Transfer Time 67 A typical dat
Page 79 and 80: Examples of Peer-to-Peer Applicatio
Page 81 and 82: B HART Communication Overview 72 HA
Page 83 and 84: 2008-04-01 Automation, Software and
Page 85 and 86: 2008-04-01 HART Position Paper from
Page 87 and 88: 2008-04-01 A possible impact to the
Page 89 and 90: 2008-04-01 HART Position Paper from
Page 91 and 92: C Safety-Critical Function Blocks O
Page 93 and 94: SYS_CRITICAL_IO Accumulates the sta
Page 95 and 96: Library Trident and Tri-GP (TRDLIB)
Page 97 and 98: END_IF ; PREVIOUS_RESET := RESET ;
Page 99 and 100: Output Parameters (continued) Name
Page 101 and 102: SYS_SHUTDOWN 91 * the safety system
Page 103 and 104: ALARM_DISABLED_POINTS := MPX.POINTS
Page 105 and 106: Example For shutdown examples, see
Page 107 and 108:
A abbreviations, list of viii actua
Page 109 and 110:
message errors, external communicat
Page 112:
Invensys Operations Management 5601
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