User manual

PID Loop Operation
(DL450 Only)
Maintenance
and Troubleshooting
8--2
PID Loop Operation (DL450 only)
DL405 User Manual, 4th Edition, Rev. A
DL450 PID Control
Along with control functions discussed in this manual, the DL450 CPU features PID
process control. The primary features are:
S Up to 16 loops, individual programmable sample rates
S The use of 16-- bit analog inputs and outputs
S Manual/Automatic/Cascaded loop capability available
S Two types of bumpless transfer available
S Full-featured alarms
S Ramp/soak generator with up to 16 segments
S Auto Tuning
NOTE : The D4--450 CPU requires at least DirectSOFT32, version 3.0c, build 58 or
later and CPU firmware version 1.9 (HB) and 2.446 (SH) or later to implement these
features. DirectSOFT 5 is the latest programming software. See our website for
more information www.automationdirect.com.
The DL450 CPU has process control l oop capability in addition to ladder program
execution. You can select and configure up to sixteen loops. All sensor and actuator
wiring connects directly to DL405 analog modules and digital output modules. All
process variables, gain values, alarm levels, etc., associated with each loop reside
in a Loop Variable Table in the CPU. The DL450 CPU reads process variable (PV)
inputs during each scan. Then it makes PID loop calculations during a dedicated
time slice on each CPU scan, updating the control output value. The control loops
use the Proportional-Integral-Derivative (PID) algorithm to generate the control
output command. This chapter describes how the loops operate, and what you must
do to configure and tune the loops.
Analog Input
Analog or Digital Output
DL450 CPU
Manufacturing Process
PID Loop Calculations
As withDirectSOFT32, DirectSOFT 5programming software, version 5.0 or later, is
used for configuring analog control loops in the DL450. DirectSOFT uses dialog
boxes to help you set up theindividual loops. Aftercompleting the setup, you can use
DirectSOFT’s PID View to tune each loop. The configuration and tuning selections
you make are stored in the DL450’s V--memory, which can be set as retentive. The
loop parameters also may be saved to disk for recall later.
DL450 PID Control
Features