Rockwell Automation AADvance Controller Safety Manual User Manual
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Document: 553630
ICSTT-RM446K-EN-P Issue: 10
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I/O Module Process Safety Time (PST)
This option allows the system integrator to configure the PST for an I/O
module, independently from the system value set through the processor
module. If no independent value is set for the module it will adopt, by default,
the top level value of PST set for the processor module. When an input
module exceeds the PST, that is the controller does not receive an update
from the I/O module within the PST then the I/O module is set to a fail safe
state and returns safe values to the controller (refer to the topic - Input
Modules Safety Accuracy).
Digital/Analogue output module PST
For a digital/analogue output module the PST represents the period of a
watchdog timer that specifies the length of time the controller will allow the
module to run without receiving updates from the application. If the module
runs beyond this time without receiving any updates, it enters its shutdown
state. The default PST is 2500ms.
Input Module Safety Functions
An input module is classified as safety critical and is designed to SIL3 level as a
single fail safe module. The input modules offer 8 or 16 isolated channels and
reports input voltage levels to the processor, for the analogue input variant the
module will convert the field current into a voltage. Input values are updated
by the workbench at least once per application cycle. The same hardware is
used for the 24Vdc digital input modules and the 4- 20mA analogue input
module.
I/O modules can be replaced or installed on-line without affecting the
controller operation provided at least one is fitted and is fully operational.
However, each module must be installed one at a time and allowed to educate
before the next module is installed.
The input module will operate in a SIL2 or SIL3 configuration for energize to
action and de-energize to trip applications The module provides the following
isolation:
channel to channel galvanic isolation
galvanic isolation between channels and the communication signals
galvanic isolation between channels and power
locking screw operational function