Red Lion DLC - Manual (Page 17)

17
ANALOG OUTPUT CALIBRATION
Calibration Type: This specifies the Analog Output point to be calibrated.
Volts: Analog Output Voltage calibration requires a precision meter with an accuracy of 0.05% (or better)
that is capable of measuring 10.00 V.
mA: Analog Output Current calibration requires a precision meter with an accuracy of 0.05% (or better)
that is capable of measuring 20.00 mA.
Meter Value: After pressing the Calibrate button, this shows the value the DLC is outputting. Measure the
actual output with an external meter and enter that value here. Press the Calibrate button again and follow
the prompts.
Calibrate: The Calibrate button initiates the calibration process after the appropriate settings are selected.
APPLICATION
A plastic extrusion company was building a four-zone extruder, and wanted a centrally located,
multi-zone interface. The interface needed to display the temperature and setpoint values, as well as
the screw RPM and barrel pressure. The customer provided a speed proportional 0-10 Volt signal
from a motor drive, and installed a 4-20 mA output pressure sensor in the extruder barrel. Each of
the four heat/cool zones were equipped with a thermocouple.
Three DLC-Dual Loop Controllers, with a G3 HMI, allowed the customer to build his own control
system. Only three DLCs were required; two were needed to control the four temperature zones, and
one was needed to monitor the two process signals.
All three units were
connected to the RS485
port of the G3 display. The
customer created his own
displays on the HMI,
which allowed him to
monitor and control the
setpoints and alarms
within the DLCs. The G3’s
multi-protocol capability
allowed it to tie the DLCs
to his PLC, creating a true
centralized interface.
CONTROL MODE EXPLANATIONS
MANUAL CONTROL MODE
In Manual Control Mode, the controller operates as an open loop system
(does not use the setpoint and process feedback). The user enters a percentage
of power through the Output Power register (40005/40021) to control the heat
(reverse) or cool (direct) for Output OP1. When Alarm 2 is configured for
Cooling (OP2), Manual operation provides 0 to 100% power to OP1 (heating)
and -100 to 0% power to OP2 (Cooling). The Low and High Power limits are
ignored when the controller is in Manual.
For time proportional outputs, the output power is converted into output On
time using the Cycle Time. For example, with a four second cycle time and 75%
power, the output will be on (4 × 0.75) for three seconds and off for one second.
For Analog Outputs (0-10 VDC or 0/4-20 mA), the percent output power is
converted into a linear value according to the Percent Low and High scaling set
for the analog output. For example, with 0 VDC (scaled 0.0%) to 10 VDC
(scaled 100%) and 75% power, the analog output will be 7.5 VDC.
MODE TRANSFER
When transferring the controller mode from or to Automatic, the controlling
outputs remain constant, exercising true bumpless transfer. When transferring
from Manual to Automatic, the power initially remains steady, but Integral
Action corrects (if necessary) the closed loop power demand at a rate
proportional to the Integral Time. The Control Mode can be changed through
the Control Mode register (40041/40049).
AUTOMATIC CONTROL MODE
In Automatic Control Mode, the percentage of output power is automatically
determined by PID or On/Off calculations based on the setpoint and process
feedback. For this reason, PID Control and On/Off Control always imply
Automatic Control Mode.
PROTOCOL
MODBUS RS485 RS485
PROTOCOL
MODBUS RS485 MODBUS
PROTOCOL
ZONE 4 ZONE 3
FOUR-ZONE EXTRUDER
POWER
18-36VDC/
24VAC
0-10V SIG.
4-20mA SIG.
(FROM PRESSURE
(FROM MOTOR DRIVE)
+
SENSOR)
HMI UNIT
+ +
ZONE 2
+
ZONE 1
MODEL DLC
RED LION CONTROLS
MODEL DLC RED LION CONTROLS MODEL DLC RED LION CONTROLS