Emerson Rosemount 3490 Series Reference Manual page 115

Reference Manual
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Table 4-21: Custom Mode Relay Parameters
Parameter
P250
P251
P252
P253
P254
P257
Table 4-22: P250/P251/P252 Options
Options
None
Time
PV > Level
PV < Level
Ext Trig
Ext Trig Xs
(1) This does not require Digital Input IN1 or IN2 to be allocated an action.
(2) Abbreviations: "Ext Trig" = External Trigger (Digital Input).
Emerson.com/Rosemount
Description
Start On Relay energizes when the selected condition is true.
See also
Stop On Relay de-energizes when the selected condition is
true. See also
Stop If Relay de-energizes when the selected condition is
true. See also
Start Time This defines the clock time for when a Custom mode
relay operation will begin (if P250 = Time) or end (if
P251 = Time).
Interval This is for defining the interval for repeating a
Custom mode relay operation.
P255 and P256 are for setting up a second starting
time and an associated interval.
Max Retries This defines the maximum number of failed
attempts to perform Custom mode relay operations
before it is deemed an alarm condition.
The alarm condition can happen if the control unit is
in Program mode, which prevents all Custom mode
relay operations from starting. Also, it can happen
when the maximum time for an energized relay has
been reached and is preventing a Custom mode
relay operation from completing.
Purpose of option
Switched off.
P253 and P254 determine when a Custom
mode relay is to be energized.
Energize a Custom mode relay when the
control unit PV value (D800) is greater
than the relay On Point.
De-energize a Custom mode relay when
the control unit PV value (D800) less than
the relay On point.
(1)(2)
Energize a Custom mode relay when a
digital input is active.
(1)(2)
When a Digital Input is active, de-energize
a Custom mode relay after X seconds
delay.
Table 4-22.
Table 4-22.
Table 4-22. P252 is a fail-safe for P251.
Getting started
January 2021
Factory default
None
None
None
"7:00" - i.e. 7AM
"1:00" i.e. 1hr
0min
10
Start on Stop on Stop if
(P250) (P251) (P252)
Yes Yes Yes
Yes Yes N/A
Yes N/A N/A
N/A Yes Yes
Yes Yes Yes
N/A N/A Yes
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