Emerson Rosemount 3490 Series, Reference Manual

Page: 97 / 190

Table 4-9: Relay Modes
(continued)
Relay mode Purpose of relay mode Auxiliary
functions
Digital input 1+2 Relay is energized while Digital Input 1 (IN1) and 2 (IN2)
are both active. Yes
Off Relay is always de-energized. No
Set Point On/Off Point Control using PV (D800). Yes
Alarm Relay is allocated to alarm indication duty. Yes
Hi or Lo Alarm High alarm limit (using On/Off Point Control):
• The On Point must be greater than the Off Point.
• Relay energizes when the PV (D800) is greater than the
On Point.
• Relay de-energizes when the PV (D800) is less than the
Off Point.
Yes
Low alarm limit (using On/Off Point Control):
• The On Point must be less than the Off Point.
• Relay energizes when the PV (D800) is less than the Off
Point.
• Relay de-energizes when the PV (D800) is greater than
the On Point.
An “A” is shown by the RL1 icon status (on the Full PV
Display) when there is a high or low alarm. (The section
Set-up alarms is not applicable).
Totalizer (Rosemount 3491 only) Relay outputs totalizer pulses. No
Totalizer 1 (Rosemount 3492/3493 only) Relay outputs totalizer 1
pulses. No
Totalizer 2 (Rosemount 3492/3493 only) Relay outputs totalizer 2
pulses. No
Fault Indicate fault condition by de-energizing relay. No
Custom Custom relay operation. No
PV limits Relay energizes while control unit PV value (D800) is
within on/off point limits. Yes
On Relay is always energized. No
Auxiliary functions for relay modes
Relay modes automatically enable and disable special control functions, special alarms
and pumped volume totalizing as shown in
Table 4-10 and Table 4-11 .
Reference Manual Getting started
00809-0100-4841 January 2021
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