PCU01000 Datasheet, PDF (31/96 Pages) Red Lion Controls. Inc – THE PROCESS CONTROL UNIT

Setpoint Limit Values (SPLO & SPHI)
The controller has programmable high and low setpoint limit values to
restrict the setting range of the setpoint. Set the limit values so that the
setpoint value cannot be set outside the safe operating area of the process. On
models equipped with Second Analog Input, configured as a Remote
Setpoint, the Remote Setpoint reading is also restricted to these limits.
SPLO - -999 to 9999
SPHI - -999 to 9999
Setpoint Ramp Rate (SPrP)
The setpoint can be programmed to ramp independent of the controller’s
decimal point position and rounding increment. The setpoint ramp rate can
reduce sudden shock to the process, reduce overshoot on start-up or setpoint
changes, or ramp the process at a controlled rate.
SPrP - 0.1 to 999.9 units/minute
A ramp value of zero disables setpoint ramping. If the optional user input is
programmed for setpoint ramp, it affects the enabling and disabling of
setpoint ramping (See User Input, page 23). Setpoint ramping is initiated on
power-up or when the setpoint value is changed and is indicated by a decimal
point flashing in the far right corner of the main display.
Figure 13, Setpoint Ramp Rate
Once the ramping setpoint reaches the target setpoint, the setpoint ramp
rate disengages until the setpoint is changed again. If the ramp value is
changed during ramping, the new ramp rate takes effect. If the setpoint is
ramping prior to invoking Auto-Tune, the ramping is suspended during
Auto-Tune and then resumed afterward using the current display as a starting
value. Deviation and band alarms are relative to the target setpoint, not the
ramping setpoint. If the analog output is programmed to transmit the setpoint
value, the instantaneous ramping setpoint value is transmitted.
Note: Depending on the ramp rate relative to the process dynamics, the actual
scaled process value may not track the ramping setpoint value.
On models equipped with Second Analog Input, configured as Remote
Setpoint, this parameter may be used to establish a maximum rate of change
of the Remote Setpoint reading. If the controller or transmitter that supplies
the Remote Setpoint reading is swinging too wildly, or changing too fast,
resulting in control problems, the ramp rate can be used to reduce the rate of
change of the Remote Setpoint reading. When ramping in Remote Setpoint
operation, the flashing decimal point is suppressed. The units of ramping for
Remote Setpoint operation are 0.1 to 999.9 LSD/minute.
User Input (InPt)
The user input may be programmed to perform a variety of controller
functions. The input must be in its active state for 100 msec minimum to
perform the function. The unit executes all functions in 100 msec, except the
print request function that requires 110 to 200 msec for a response. A function
is performed when the User Input, (Terminal 7) is used in conjunction with
common (Terminal 10).
Note: Do not tie the commons of multiple units to a single switch. Use either a
multiple pole switch for ganged operation or a single switch for each unit.
Below is a list of the available functions.
PLOC - Program Lock. A low level enables the program disable function
which places the unit in the Protected Parameter Mode.
Note: Front panel disable is possible without using this program lock
function, see Front Panel Program Disable, page 19.
ILOC - Integral Action Lock. A low level disables the integral action of the
PID computation. A high level resumes the integral action.
trnF - Auto/Manual Transfer. A negative transition places the unit in the
manual (user) mode and a positive transition places the unit in the
automatic operating mode. The output is “bumpless” when transferring to
either operating mode.
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