Simple Fiber System

ITT Goulds offers a system called Pro Smart, which may be overkill, but is simple to install. It uses 2.4Ghz RF from remote data monitors linked to a communication module. The comm module connects via LAN to your DCS. The data monitors commutate 22 channels of data on the unit being monitored. RF link distance is 1.6 miles line of sight.

Emma Chizzit?

The Data Module is ~ $5,300 U.S. Comm Module is ~$2,300 for LAN, and ~$2,800 for GSM/GPRS Cellular Modem version.

The latter is cool because you don't even need a network. The Comm Module will text, or email you when an alarm condition occurs.

Anyway, the above cost is essentially free if it prevents one system failure...

And, you don't have to pull any wire :)

In alarm signals, the alarm should also 'trip' if the signal is broken to alert the user(s) there is a problem - just in case there is a problem occurring while the system itself has a fault. This is where 'radio' signal could fall as it is more susceptible to external factors of interference and the like. This is where I would choose fiber.

In general, multimode fiber is good for up to 2-3km and a lot cheaper per meter and singlemode for greater distances up to about 100km but more expensive per meter. I'm not sure on the prices.

As for a reputable manufactuer, try www.osd.com.au. They have a fiber modem exactly for that type of use called the OSD158. http://www.osd.com.au/english/products/view/?id=15. I don't think that it is that expensive ~ around $500-$600 for each end (transmitter/receiver). Also take into account the conversion rate and it is even cheaper. (sorry for the plug - but it was requested)

From my experience in electrical engineering fiber is the least reliable transmission media. Fiber cables don't handle shock or flex very well. The benefit to fiber is near infinite bandwidth. Bandwidth in this application is of no use, since we are taking seconds, not microseconds for a data update.

The RF system above sends a data packet every 5 seconds 24/7/365. If the packet stream is interrupted the Comm Module flags the DCS or the Controls Engineer via WiFi.

My second choice after RF would be copper with a 4-20 ma current loop.

Least Reliable? Your joking! Sure it requires protection from shock...That's why there is a sleave and then usually in some sort of conduit. You are talking about 'bare fiber'. It shatters cause it's glass.

As for least reliable...Then why are their thousands of fiber cables sitting across continents on the sea bed? Why are broadband networks moving towards fiber? Train signaling/highway monitoring/security/surveillance is all currently being changed over from copper to fiber.

From my electrical engineering experience, fiber is secure, fast, reliable, large bandwidth, etc.

Sorry for the flame-up

I am curious as to the experience you cite that fiber is the least reliable transmission media. In my experience, it is the MOST reliable, and experienced installers have no problem with installation or handling whatsoever. The cost of installation of fiber has been considerably less than for copper for a number of years. One need only look at the size difference between TAT7 (The seventh transatlantic telephone cable installed, all copper) and the TAT8 (first fiber optic transatlantic cable) to understand why fiber is much cheaper to install.

The incentive for moving from copper to fiber is bandwidth. All the comm systems you mentioned above have data packets backed up, and there are always alternate paths.

If you only have one data path, and alarms are one shot alarms, my choice would be copper every time.

The original request was radio or fiber...not copper.

Personally, I would choose copper for most applications...cheaper, easier to work with, less hassles and anyone can fix it...not specialized experience.

I have had very good luck with very inexpensive RF links, but did not have the advantage of preinstalled conduit to make the connections. The previous comments in the thread also tend to ignore the inherent noise immunity enjoyed with fiber- which would give it a leading edge over RF or copper for some applications.