Allen-Bradley GuardPLC 1753, Справочник по безопасности

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Publication 1753-RM002C-EN-P - September 2008 19
Safety Concept for GuardPLC Controllers and GuardPLC I/O Chapter 1
Communication
•
The total response time of the system must not exceed the fault
tolerance time when safety communication occurs between
devices.
•
Safety data cannot be transferred over public networks (for
example, the Internet).
•
if the data is transferred across company/factory networks, verify
that sufficient protection is provided against manipulation. For
example, use a firewall or router to separate the standard or
safety I/O subnets from office subnets in your environment.
Refer to Safety Concept of RSLogix Guard PLUS! Software on
page 77 for more information.
•
Equipment connected to communication devices should feature
safe electrical isolation.
•
Your application should monitor the status bits associated with
safety network connections. Since connections often recover
automatically, make sure this occurrence does not result in an
unsafe machine state. Your application should drive safety
outputs to their safe state when the connection faults or goes
idle. Safety outputs remain in the safe state until a manual reset
occurs. This prevents unexpected output transitions from low to
high when a connection recovers from a faulted or idle state.
Maintenance Override
When using Maintenance Override, follow the requirements of the
most recent version of the Maintenance Override document from the
TÜV Homepage:
http://www.tuv-fs.com (TÜV Rheinland).
If necessary, the operator must consult the acceptance department
responsible for the application to determine the administrative
requirements to provide access protection for the system.
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