Safety Considerations Guide for Trident v2 Systems - TUV ...
Safety Considerations Guide for Trident v2 Systems - TUV ...
Safety Considerations Guide for Trident v2 Systems - TUV ...
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When Some I/O Modules Are <strong>Safety</strong>-Critical<br />
Sample <strong>Safety</strong>-Shutdown Programs 55<br />
For some applications, not all modules may be critical to a process. For example, an output<br />
module that interfaces to the status indicators on a local panel is usually not critical to a process.<br />
The EX02_SHUTDOWN sample program shows how to increase system availability by<br />
detecting the status of safety-critical modules. The user-defined function block CRITICAL_IO<br />
checks the safety-critical I/O modules. The CRITICAL_IO outputs are connected to the inputs<br />
of the CRITICAL_MODULES function block.<br />
Note The sample program is an element of project Td<strong>TUV</strong>.pt2 included as part of the<br />
TriStation 1131 software installation. The default location of the project is C:\Documents<br />
and Settings\\My Documents\Triconex\TriStation 1131 4.x\Projects.<br />
When the output CRITICAL_MODULES_OPERATING is true, all critical modules are<br />
operating properly. The input MAX_TIME_DUAL specifies the maximum time allowed with<br />
two channels operating (with no connection, defaults to 40000 days). The input<br />
MAX_TIME_SINGLE specifies the maximum time allowed with one channel operating (three<br />
days in the example).<br />
Note In typical applications, the operating time restrictions in the table on page 25 should be<br />
followed.<br />
When CRITICAL_MODULES_OPERATING is false, the time in degraded operation exceeds<br />
the specified limits; there<strong>for</strong>e, the control program should shut down the plant.<br />
CAUTION<br />
Program EX02_SHUTDOWN<br />
CRITICAL_IO<br />
EX02_CRITICAL_IO<br />
CI<br />
RELAY1_OK<br />
001<br />
CO<br />
TMR<br />
GE_DUAL<br />
GE_SINGLE<br />
NO_VOTER_FLTS<br />
ERROR<br />
T#3d<br />
T#400ms<br />
EX02_SHUTDOWN does not handle detected field faults, rare<br />
combinations of faults detected as field faults, or output voter faults<br />
hidden by field faults. The application, not the SYS_SHUTDOWN<br />
function block, must read the NO_FLD_FLTS module status or FLD_OK<br />
point status to provide the required application-specific action.<br />
CRITICAL_MODULES<br />
SYS_SHUTDOWN<br />
CI<br />
CO<br />
IO_CO<br />
OPERATIING<br />
IO_TMR<br />
TMR<br />
IO_GE_DUAL<br />
DUAL<br />
IO_GE_SINGLE<br />
SINGL<br />
IO_NO_VOTER_FLTS<br />
ZERO<br />
IO_ERROR<br />
TIMER_RUNNING<br />
MAX_TIME_DUAL<br />
TIME_LEFT<br />
MAX_TIME_SINGLE ALARM_PROGRAMMING_PERMITTED<br />
MAX_SCAN_TIME<br />
002<br />
ALARM_REMOTE_ACCESS<br />
ALARM_RESPONSE_TIME<br />
ALARM_DISABLED_POINTS<br />
ERROR<br />
Figure 11 EX02_SHUTDOWN Sample Program<br />
CRITICAL_MODULES_OPERATING<br />
ALARM_PROGRAMMING_PERMITTED<br />
ALARM_REMOTE_ACCESS<br />
ALARM_RESPONSE_TIME<br />
ALARM_DISABLED_POINTS<br />
<strong>Safety</strong> <strong>Considerations</strong> <strong>Guide</strong> <strong>for</strong> <strong>Trident</strong> <strong>v2</strong> <strong>Systems</strong>
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