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| The
ACTOReX™ /e-ACTOReX™ survey. |
The process
control concept implies an intentional interaction between a real physical world
process and a managing entity. The process supplies information under physical
parameters appearance and supports actions from the managing entity.
In-between the process and the managing entity - in this case, the
computer - interleave a process interface that acquire information,
transmit it to the host computer and convey the decisions to the process under
the appearance of actions.
A more detailed structure of the interface
block allows specifying the ACTOReX™ product place and role in the process
control feedback loop.
The physical parameters must be converted to electrical signals appropriate
to be translated to the computer understanding. Transducers perform the conversion
of physical parameters into electrical signals. The transducers supply, generally,
analog signals dynamically conveying quantitative information (as temperature,
force, displacement, speed, etc.) and steady signals conveying status information
(as impact, position, threshold reaching, success, failure, etc.).
The
actuators, conversely, are able to receive information in electric format,
analog (as brake force, displacement, rotation, light intensity, etc.) or steady
(as ring alarm, valve opening, relay contact closing, etc.), conveying them to
the physical process as appropriate action parameters.
The signals produced
by the transducers, as well as the electrical signals accepted by actuators, range
in a wide diversity of electrical properties. In other words, these signals are
non-standard.
The signals conveying status information are of steady-state
nature, namely status information, as well as of the nature of "how many
time a particular status occur into a determined lap of time", namely counting.
Devices as ACTOReX™ are standard oriented in order to accommodate a
large assortment of transducers, actuators and computer types. They accept standard
signals to process in order to transmit them to the host computer and provide
standard signals to the actuators. The accommodation of transducers and
actuators electrical signal to standard electrical signals is performed by the
signal conditioning circuitry.
The role of devices as ACTOReX™
is to transmit signals, analog (quantitative and status) to the computer in digital
format and receive the computer commands in digital format and forward them to
actuators, via signal conditioning, in analog (quantitative and status) format.
The conversion of the quantitative expression of acquired signals in digital
format is called analog-to-digital conversion. The conversion of digital
quantitative expression of command to analog format is called digital-to-analog
conversion. The conversion, forth and back, of steady state information between
process and computer is called digital input/output and, respectively,
counting.
ACTOReX™ and comparable devices perform
analog-to-digital conversion of input analog signals, seize status and count events
from the process. They also perform digital-to-analog conversion of quantitative
commands, forward status information and status commands to the process.
ACTOReX™ and comparable devices do not only convey data forth and back. They
are called "intelligent" because they are capable also to process raw data and
present it to the computer as logically interpreted information. They can even
facilitate the task of the application running on the host computer by closing
decision loops and elaborating response commands without the computer implication.
At the limit ACTOReX™ can perform, by its own, process control.
Another intelligent task of ACTOReX™ is to manage its hardware resources
(analog-to-digital converters, digital-to-analog converters, counters, input/output
information registers, a.s.o.), understand the computer requirement of data and
action, and manage the data communication with the computer.
The ACTOReX™
is microcontroller driven and programmable, has several channels of data
analog-to-digital and digital-to-analog conversion, counting, and logical input/output
processing. It communicates with the host computer via the high-speed serial USB
port.
In order to perform all its tasks, actually, ACTOReX™ has
two major components: the acquisition and action subsystem and the microcontroller
subsystem.
The acquisition and action subsystem comprises all the data acquisition
and command initiation circuitry. The microcontroller subsystem manage all the
hardware facilities, manage the communication with the host computer and perform
the piece of program that understand the host computer requirements and, if any,
the piece of program that made or help to the control of the process.
The ACTOReX™ use in the PC OS environment implies the interaction, through
the operating system, between the application software and the ACTOReX™ specific
device driver. In the MS Windows environment the interaction technology is based
on ActiveX device specific control.
In both cases, MS Windows as well as Linux, the application software
is written in Object Oriented high-level programming language. The application
software calls the device specific driver objects methods.
The e-ACTOReX™
version uses a micro-PC type controller on the ACTOReX™ data acquisition
and action generation device. The ACTOReX™ general features are still available
on e-ACTOReX™ version, but the presence of the local micro-PC module allow
the following extended features:
- the "host computer" can be a remote
PC but, as well, the micro-PC itself running the high level OS controlled application
software;
- the presence of local human interfaces as monitor, keyboard,
mouse, etc. at the e-ACTOReX™ controlled process place;
- the Ethernet
connectivity of the e-ACTOReX™ device with a remote computer or server in
order to establish complex networked process control setup's;
- the remote
controlled web-based application hosted on the e-ACTOReX™ micro-PC.
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