FOXBORO 743CB-DF 743CB Series
From:
|
Author:kongjiangauto
|
Time :2019-04-26
|
857 Browse:
|
Share:
FOXBORO 743CB-DF 743CB Series
743CB Series
FIELD STATION MICRO Controller
The 743CB is a self-contained, field-mounted,
microprocessor-based controller with the ability to
perform control functions for up to two independent
loops. In addition to the standard proportional,
integral, and derivative (PID) functions, the controller
provides many enhanced functions including
Foxboro’s patented EXACT tuning algorithm, user-
configurable control functions, auto selector control,
split range outputs, auto/manual transfer stations,
assignable 3-variable indicator functions, totalization,
a comprehensive calculation capability, and signal
conditioning. Standard controller signals include: four
analog inputs, two frequency inputs, two contact
inputs, an optional platinum RTD direct input, two
analog outputs, and two contact outputs.
A fluorescent display is used to show the control
variables in bargraph format, and to provide precision
digital readout. It also displays an electronic loop tag,
controller status, and alarm indication. A keypad,
located on the front of the controller, is used for
operator interface and configuration.
The controller is housed in a field-mounted enclosure
that meets IEC IP66 and that also provides the
environmental and corrosion resistant protection of
NEMA Type 4X. The enclosure can be mounted to a
surface or panel, or mounted to a nominal DN50 or
2 in pipe.
FEATURES
• Two Independent PID Controllers
• Single Station Cascade Control
• Single Station Auto Selector Control
• Split Range Outputs
• Ratio Control
• Batch (Discontinuous) Control
• Totalization
• 3-Variable Indicators
• Auto/Manual Transfer Stations
• Assignable Alarms
• Algebraic Computation
• Dynamic Compensation with Lead/Lag, Impulse,
and Dead Time Functions
• Boolean Logic Capability
• EXACT Control (Foxboro U.S. Patent RE 33267)
• Flexible Configuration Blocks with Internal Signal
Routing
• Fully Interactive Display
• Configuration and Display of an Independent
Variable
• Pulse Driven Input
• RS-485 Serial Communications for Operation
and Configuration
• Nonvolatile Memory
• Transportable Configuration
• Power Failure Recovery Logic
• Front Panel Keypad for Both Configuration and
Operator Interface
• Internal Signal Sources for Calibration
• Integral Field Power Supply
• Passcode Security
TWO INDEPENDENT CONTROLLERS
Two completely independent control strategies can be
used. All control support functions are available for
both loops, thereby allowing high-performance,
enhanced control of each loop.
CASCADE CONTROL
With this controller configuration, the output of one of
the controllers (primary controller) drives the set point
of the other (secondary) controller. This configuration
can improve the performance of certain control loops
where load disturbances are a factor.
AUTO SELECTOR CONTROL
Two controllers with a single selected output are
combined in this configuration to provide constraint
control or dual mode control. The choice of lower,
higher, or logic-selected output is configurable. The
inherent design prevents controller windup and offers
independent or interlocked auto/manual functions.
SPLIT RANGE OUTPUTS
The two 4-20 mA outputs can be driven from a single
controller. This allows one measured variable to be
controlled by two manipulated variables. A typical
application is a temperature control system in which
both the heating medium and the cooling medium are
manipulated.
ACTUAL OUTPUT INDICATION
The output bargraph and digital indicator can be
configured to display the actual 4-20 mA output value,
or any analog signal, such as valve position
feedback.
TOTALIZERS
Up to two 7-digit totalizers are available. The
totalizers can be set to integrate up to a preset value
or down from a preset value, and produce a logic
event output. Any internal or external signal can be
totalized.
Totalization and EXACT tuning are mutually
exclusive. For example, if one controller is configured
for EXACT tuning, only one totalizer is available.
EXACT CONTROL
EXACT control uses microprocessor technology to
make ongoing controller adjustments based on the
actual, real time process dynamics. This is in direct
contrast to other “self-tuning” controllers that establish
the values of tuning parameters based on an arbitrary
process model.
While continuously scanning the process variables,
EXACT control initiates corrective action upon
sensing a process upset. The user selects the
desired response by specifying the desired damping
and overshoot-to-load change, such as quarter
amplitude damping.
Values of EXACT can be read by the user.
EXACT control functions as if your best operator is on
the job 24 hours a day. It can be turned on or off at
the keypad or by configuring logic functions, allowing
these controllers to function as advanced PID
controllers.
EXACT control is available on both control loops.
3-VARIABLE INDICATOR
Up to two 3-variable indicator faceplates are
available. Each variable has its own bargraph, digital
engineering units, and loop tag. The 3-variable
faceplates are mutually exclusive with controllers and
auto/manual stations. If only one controller or manual
station is configured, one 3-variable faceplate will be
available.
AUTO/MANUAL TRANSFER STATION
Up to two auto/manual stations are available.
Auto/manual stations are mutually exclusive with
controllers and indicators. For example, if only one
indicator or manual station is configured, one
auto/manual station will be available.
PULSE DRIVEN INPUT
There is provision for two pulse inputs, forming a
pulse up/pulse down pair that can be assigned to any
scaled signal such as remote set point. This function
is compatible with the signals used for older stepping
motor type devices.
RS-485 SERIAL COMMUNICATIONS INTERFACE
This controller is equipped with an RS-485 serial port
for communication with most host computers, either
directly or via an RS-232/RS-485 converter or
equivalent accessory. Protocol conforms to ANSI
Specification X3.28-1976, Subcategory E3. Using the
Foxboro Model F6501A converter, up to 90
controllers can be accommodated with a single host
communication port.
Serial communications capability includes
uploading/downloading of configuration, setting of
Auto/Manual (A/M) or Remote/Local (R/L) status and
manual output and local setpoint values, polling of all
inputs, outputs, and totalizers, and writing as well as
reading of all configurable parameters. Both control
loops are accommodated. The user can also select
parity, and panel, workstation (host), or “both” priority.
COMPUTATIONAL CAPABILITY
This controller performs up to three independent
calculations. The variables may include the results of
other calculation blocks, scaled and conditioned
inputs, and other internal control signals.
An equation is entered from the keypad one character
at a time following the usual rules of algebra and a
few easy-to-learn rules. The result of this flexibility is
exceptional computational capability in a single
station controller.
SIMPLIFIED CONFIGURATION AND OPERATION
Because of its flexibility, this controller is easily
configured to meet the most exacting process
requirements. All operating functions are examined
and/or changed by keystrokes. Interactive prompting
simplifies setting the adjustable parameters.
COMPLETE SECURITY
The operator has keypad access to read the values of
inputs, alarm and limit settings, and the operating
configuration. However, the operator can adjust only
those settings which were specified as operator-
adjustable when the controller was configured. A
passcode must be entered from the keypad to enable
adjustment of the remaining parameters. In addition,
a keypad disable jumper, accessible from inside the
tamper resistant enclosure, is provided.
This passcode is determined by an authorized person
at the time the controller is configured. Thus, only
those who have been given this passcode can
change any of the protected parameters.
BOOLEAN LOGIC CAPABILITY
There are five single gates and five dual gates. Each
gate is configured by selecting the logic and then
selecting the source of each input. Gates 0 through 4
are the single input gates and are configured DIRECT
or NOT by the user. Gates 5 through 9 are the dual
input gates and the user selects one of the following
logic types for each one: OR, NOR, AND, NAND,
XOR, or XNOR.
DYNAMIC COMPENSATION
The result of a dedicated calculation block can be
passed through a dynamic compensator, prior to
distribution. The dynamic compensator provides
lead/lag, impulse, and dead time functions, each with
its individual follow (bypass) switch. Functionally,
dead time precedes lead/lag and is the input to the
lead/lag function.
Utilizing the dynamic compensator and the follow
switches, feedforward and other complex control
applications are easily and efficiently handled.