Supervisory Control and Data Acquisition (SCADA)




SCADA "Supervisory Control and Data Acquisition"


Is it something to fear or just be cautious of?


Written by Jeff Dominique, FNT Consulting & Training



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 harsh environments.


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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