The next time you
have an opportunity to bid a SCADA job; don’t be in such a panic. It’s still comprised of ordinary fiber cable,
ordinary fiber termination components, and a simple RS connection to the data I/O
Input / Output device.
SCADA systems are
used by water treatment plants, water well heads, natural gas and virtually any
industry that requires interfaces between the operator and controlling or monitoring
devices. SCADA has a unique built in
feature that enables the controlling element to store settings for running a
like or similar command on future events.
SCADA often uses a
very old concept of Bus Topology sometimes referred to as Token Ring, where
each of the add/drop units (often referred to as repeaters) is configured with
two sets of fiber optic or Category copper transmit/receive ports. What media cable is used strictly depends on
the distance to the next unit/repeater in line, as SCADA is typically a low
data rate transfer system that is spread out over a considerable distance.
Since data rates are
often so low, a low data rate fiber is most often the preference. The fiber type is usually multimode, which
can effectively transmit 10 megabits per second for 2 to 3 kilometers and even
further on professionally installed systems. Connectors on the equipment itself are usually legacy ST due to their
popularity at the time also when SCADA was popular. Additionally, SCADA often supports equipment
such as programmable controllers, which in turn monitors sensor data and activates
operational relays to turn things on and off, like pumps and valves. SCADA systems were state of the art at the
point of their introduction because they were simple, reliable and effective in
Contrary to the
belief of SCADA system operators, issues typically begin due to their
confidence in the system and lack of checking network components. Additionally, Structured Cabling Standards
did not exist when many SCADA systems were installed. Odds are slim on modern day conveniences,
such as slack cable being available to work with. Also, with SCADA systems
usually only employing two fibers in and two fibers out, termination panels
with the appropriate number of ports are far and few between, often leading to
several unused connectors stored un-terminated in the bottom of the box.
Let’s review this
for a second; old technology, old connectivity components, undersized patch
panels, harsh environment use, few or no Standards Documents to direct the
original installation, new young operators with little to no knowledge of SCADA
and maintenance staffs that are about to retire. This sounds like a recipe for disaster, but
it doesn’t have to be. Fiber is still fiber
and you know how to fix it right?
If you don’t, I
suggest that you get back to school, "fiber school that is”, and learn the ins
and outs of SCADA and the many other applications for fiber. If someone requests a bid to rework a SCADA
system, you need not be afraid. Be
cautious and understand that these systems were typically built many years ago
and the equipment is often located in harsh environments. Also, be aware that the system may not look
much like the systems you are installing today.
I recommend that you
come prepared! Extra fiber connectors,
extra patch panels and connection bulk-heads may be needed to replace rotted
and / or corroded components. Also,
don’t forget the bug spray for spiders and other nasty critters hiding in the
dark, damp, unforgiving places where SCADA equipment is found.
It’s a wonder how
this fiber can work flawlessly for so long. But then again, everything has a life expectancy and this is why we are
seeing SCADA re-work bids popping up all over the place.
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