Rockwell Automation Publication 1444-UM001D-EN-P - June 2018 205
Configure Relays Chapter 7
Relay Management Overview
Relays are commonly used in a monitoring system to provide annunciation of a
change in machine condition, trip a machine, preclude start of a machine.
The relay management system provides a flexible implementation where relays
can be defined to act on:
• Any voted alarm output, which includes any faults that are implicit in
the voted alarm definition
• Any voted alarm output, which includes any faults that are implicit in
the voted alarm definition, and selected system faults
• Any selected system faults (a dedicated fault relay)
Alarm Output
Each relay can reference one voted alarm. Because the status of the voted alarm
could be an alert, danger, transducer fault, disarm, or module fault, you must
also define the specific status necessary to actuate the relay.
A voted alarm can be configured to actuate on alert, danger, and/or transducer
fault. You can also define how the measurement alarms input to the voted
alarm behaves if a transducer fault occurs. This flexibility provides the tools
necessary to define systems with relays that, for example:
• Actuate only when the voted logic is based on actual alarm level
measurements
• Actuate when the voted logic is based on alarm level or faulted
measurements
In this case, the measurement alarms are defined such that a transducer
fault is treated as “in alarm”.
•Actuate on transducer fault
Expansion Module Relay – Module Fault Checked (1) / Unchecked (0) Check this value when the relay must actuate on a fault in
either the main Module or the Relay expansion module.
When Fail-Safe Enable is checked for the selected Voted
Alarm, if Alarm Status to Activate On is set to Module Fault
this control is checked and disabled.
If the relay is configured to actuate on Module Fault only,
so no associated voted alarm, and it is the first relay on
the expansion module that is configured for Module Fault,
then the relay is configured Fail Safe (normally
energized).
Expansion Module Relay – Expansion Bus Fault Checked (1) / Unchecked (0) Check this value when the relay must actuate on a fault of
the Expansion Bus.
Expansion Module Relay – Latch Enable Checked (1) / Unchecked (0) Check this value when the relay must latch after having
actuated on any of the selected fault conditions.
Latch control for the alarm input is included in the Voted
Alarm definition.
Table 44 - Relays (continued)
Parameter Values Help
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