Allen-Bradley GuardPLC 1753, Safety Reference Manual

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Publication 1753-RM002C-EN-P - September 2008 63
GuardPLC DeviceNet Safety Scanner Chapter 5
Reaction Times
The system reaction time is the amount of time from a safety-related
event as input to the system until the system is in the Safety state.
Refer to page 103 for reaction time information.
Connection Status
Your application should monitor the HSP and DeviceNet connection
status bits. 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, and remains 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.
DeviceNet Scanner
Configuration Checklist
Use the checklist on the following page for configuration,
programming and start-up of the DeviceNet safety scanner.
It may be used as a planning draft as well as a proof. If used as a
planning draft, the checklist can be saved as a record of the plan.
To ensure that the requirements are fully and clearly satisfied during
system configuration or start-up, an individual checklist for controlling
the requirements can be filled in for every single safety output
channel in a system.
IMPORTANT
The DeviceNet connection status bits are only accurate if the
HSP connection is in the established state.
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