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3.5.3 Reversing the default control direction
The Upper Limit control action can be reversed to activate the Upper
Limit LED and relay when the reading drops
below
the Upper Limit.
Similarly, the Lower Limit control action can be reversed to activate the
Lower Limit LED and relay when the reading rises
above
the Lower Limit.
Having two Limits acting in the same direction can be very useful for
processes where the readings always drift in one direction. It allows the
operator to set the first Limit as a control point (eg to start a dosing
pump), and the second limit beyond that as an alarm point, in case the
control action was not effective.
The
pro
CHEM
-S
must be switched OFF before changing jumper
settings.
To reverse the action of the Lower Limit, and have two
Limits that activate the High and Low LED’s and relays
when the reading rises
above
the Limits, set the J3 and
J4 jumpers as shown.
To reverse the action of the Upper Limit, and have two
Limits that activate the High and Low LED’s and relays
when the reading drops
below
the Limits, set the J3
and J4 jumpers as shown.
To re-set the action of the Upper and Lower limits to
factory defaults, set the J3 and J4 jumpers as shown