What is a Process
Control System?
Can Automation help me for my particular application?
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These
are not trivial questions for newcomers. Over the years, we have
found that the industry tends to obfuscate simple concepts in order
to create marketable 'buzzwords' that help them create a niche
for their particular agenda. At Crosstec, we believe
that even though certain 'Process Control' and 'Automation' systems
have strengths and weaknesses of their own, all the systems and
all the buzzwords eventually boil down to the same basic concepts.
A control (or automation) system's hardware and
software are generally classified by an interesting sounding acronym
such as PLC (Programmable Logic Controller), PAC (Programmable
Automation Controller), SCADA (Supervisory Control and Data Acquisition),
and DCS (Distributed Control System) ... among many others. In
between all these acronyms, are other systems (and yet more acronyms)
that claim to have a combined feature set of one or more of the
basic classifications.
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For all practical purposes, we find the following
to be true:
- Basic control scenarios (and even somewhat complex ones) can
often be handled by a small to mid-sized PLC systems. More often
than not, we see PLC vendors and integrators sell a customer
a system that
is oversized for their particular need ... both for now and the
foreseeable future. This is simply a waste of money.
- When more complex and robust control scenarios are required,
a larger PLC system and SCADA package comes into play .. although
you'd be surprised at what can be done with the smaller systems
these days. Once you enter the SCADA realm, you begin to find
it easier to use recipe driven control and usually there are
integrated data acquisition systems and monitoring tools.
- For large operations, like plant wide control and monitoring,
use of a DCS is common. These allow for I/O and Operator Interfaces
to be distributed throughout the plant, often using redundant
control networks, controllers, and computer systems. Their design
often supports on-line addition of I/O, controllers
and interfaces. Data acquisition is well integrated into
the design and is standard feature (as long as you pay for it).
The design and setup of the system is often performed using a
master database that propagates throughout the control system.
This allows for a convenient single point of programming and
configuration, while the distributed nature of the hardware make
for a robust platform.
- For very fine-grained local control, often a PLC is the tool
of choice due to abundance of I/O options and extremely fast
scan times.
- However, all bets are off ... even for the small PLC hardware
you can still create very complex operator interfaces using the
various HMI (Human Machine Interface) software packages that
are available. Also, you can implement just about any data
acquisition and reporting system with any of the above systems.
- Even as there are many different hardware/software alternatives,
many different design philosophies exist as well. A current popular
buzzword is S88, whose purpose (according to the S88.01
standard) is to "define a common set of models and terminology
that can be used to describe and define batch manufacturing systems." We
are finding that many customers are prone to attach themselves
and their particular project to such a methodology blindly, without
truly investigating the impact it may have on their timeline,
documentation requirements, and up front design costs. In our
opinion, S88 is a useful tool for breaking down your
needs and formulating a design, but is sometimes not a practical
implementation method.
Since we are not affiliated or partnered with any particular
manufacturer or re-seller of control hardware and software, you
can be assured that we will help you implement your project within
a reasonable budget and scope. If your company has not
yet standardized on a particular control system vendor, Crosstec
has a good working knowledge of the strengths and weaknesses of
each alternative and can advise a system that will best suit your
needs ... both now and for the future. It is critical to ensure
that there are adequate options for future expandability at your
disposal.
With our experience across many industries, we have gained useful
knowledge to develop a practical hardware and software solution
for most functional and environmental needs.
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Crosstec has designed, programmed, and implemented complete control
scenarios using many hardware and software solutions. The links
below will guide you through a tour of the systems (and manufacturers)
we have had experience with. It's not possible to delve into all
the benefits and disadvantages of any these products here, but
we'd be happy to discuss your project to help determine the optimal
solution for you.
 Crosstec
can design, program, and build control panels for any industrial
automation application.
Deliverables
include complete specifications and CAD drawings. |
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