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3–21 Signal Conditioner
DC Power Supply
Three types of isolated DC power supplies are available to supply
an external transmitter or sensor. These are 20V rated at 25mA,
12V rated at 40mA and 5V rated at 80mA. The DC voltage is
delivered to the output 2 terminals.
Caution:
To avoid damage, don’t use a DC power supply beyond its
current rating. Purchase one with the correct voltage to suit
your external devices. See the ordering code in section 1-2.
3–22 Manual Control
Manual control may be used for the following purposes:
1. To test the process characteristics to obtain a step response as
well as an impulse response and use these data for tuning a
controller.
2. To use manual control instead of a closed-loop control if the
sensor fails or the controller’s A-D converter fails. NOTE that
bumpless transfer can not be used for an extended time. See
section 3-17.
3. In certain applications, it is desirable to supply a process with
a constant demand.
Operation:
Press until
(hand control) appears on the display.
Press for 3 seconds, then the upper
display will begin to flash and the lower
display will show . The con-
troller is now in manual control mode.
Press ; the lower display will show
and alternately where indicates output
1 (or heating) control variable value MV1 and indicates
output 2 (or cooling) control variable value MV2. Now you can
use the up and down keys to adjust the percentage values for H or C.
The controller performs open loop control as long as it stays in
manual control mode. The H value is exported to output 1
(OUT1) and C value is exported to output 2 provided that OUT2
is performing cooling function (i.e., OUT2 selects COOL).
Exception
If OUT1 is configured as ON-OFF control (i.e., PB1=0 if PB1 is
assigned or PB2=0 if PB2 is assigned by event
input), the controller will never perform manual
control mode.
Exiting Manual Control
Press keys the and the controller will
revert to its previous operating mode (may be a
failure mode or normal control mode).
Means
MV1=38.4% for
OUT1 (or heating)
Means
MV2=7.63% for
OUT2 (or cooling)
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