Curtis 1253 - Final Speed Request Parameters; SS Add Mode

22
Curtis 1253 Manual, Rev. F
e final speed request parameters define how the controller will handle multiple
requests—from more than one speed select switch or from a combination of speed
select switches and the throttle. It is this single nal calculated speed that is demanded
of the pump motor.
When multiple requests are received, the controller can add them (“Add Mode”)
or accept only the rst request (“First On Mode”), depending on how the Add Mode
parameters are set.
For 1253-4804 controllers, the controller will enter SS High Speed On mode
if the SS High Speed On parameter is set to On; otherwise, its speed request mode
is the same as above.
SS ADD MODE
e Speed Select Add Mode parameter enables Add Mode for speed select
switches SS1–SS4. Add Mode is enabled or disabled (programmed On or O)
for all four switches as a group.
When SS Add Mode is O, the controller responds to the first request it
receives and ignores—or “locks out”—any subsequent requests; this is called
“First On Mode.” If SS3 is the first speed select switch to be closed, the controller
accelerates to the programmed SS3 maximum output. If SS2 is then closed, the
controller output (and the pump speed) remain the same and the SS3 operation
is slowed because it must share the available hydraulic pressure with the SS2
operation. If two or more speed select switches are closed simultaneously, the
controller responds to the lowest-numbered switch (i.e., SS2 takes precedence
over SS3, etc.).
When SS Add Mode is On, the controller increases the pump speed in
order to maintain the level of work requested by each speed select switch input;
this is called “Add Mode,” because the individual requests are added together.
If SS3 is the first speed select switch to be closed, the controller accelerates to
the programmed SS3 maximum output. If SS2 is then closed, the controller
output (and the pump speed) increase so that each operation is performed at
the same level of eort as if it were operating alone. e controller sends the
pump the required amount of power (up to 100% of maximum output) to
provide enough hydraulic pressure to perform all the requested operations at
their individually-specified maximum speeds.
FINAL ADD MODE
Typically, some operations are controlled by speed select switches and others by
the throttle. e Final Add Mode parameter determines whether the controller
will respond to the first request it receives (either the SS request or the throttle
request) or whether it will add them. If Final Add Mode is programmed O,
the pump speed will be defined by the first request it receives (SS or throttle).
3 — PROGRAMMABLE PARAMETERS: Final Speed Request Parameters
Final Speed Request Parameters