inexpensive fiber optic ethernet?

NeverDie

Senior Member
I'm interested in replacing regular wired ethernet to my irrigation controller in the garage with a fiber optic equivalent so as to better isolate the regular network from potential lightning strikes.  Therefore, it can be very low speed if that helps keep the price down.  RF communicationwould be a different approach to getting the same result, so for now I'm wondering if something fiber optic is even worth considering.  As a plug number, let's say the range needs to be 100 feet, even though I'm sure it's less than that.  
 
I would look at some pre-terminated multi-mode (MM) cable and some SFP MM modules if you have switches that support those or a couple of MM to Ethernet Transceivers.  
 
Here's one example of a pre-term cable: 
 
http://www.discount-low-voltage.com/Cable/OM1-62-5-Preterminated-Fiber-Cables/PT6LC11R
 
Cheers
Al
 
PS Make sure the cable and equipment is the same flavor of MM.  There are a few different kinds.  I would stick with 62.5um if cost is your primary driver.
 
When I look at some of the fiber optic cable on ebay, it seems quite inexpensive.  e.g.: http://www.ebay.com/itm/CMB-ExremeNet-Fiber-Optic-Patch-Cord-Cable-30M-Multi-Mode-50-125-W-LC-/261808700413?pt=LH_DefaultDomain_0&hash=item3cf503bbfd
 
i.e. <$15 delivered for 100 feet of multi-mode patch cable.
 
I know I said ethernet, but looking into the pricing just now and seeing the two strands, it seems like it would be almost trivially easy to do serial io over it  using, say, an arduino, provided the rx/tx hardware was also easy to hookup.  That said, the ethernet converters aren't very expensive either at $33 for a converter:
http://www.newegg.com/Product/Product.aspx?Item=N82E16833704015&cm_re=fiber_optic_ethernet-_-33-704-015-_-Product
 
az1324 said:
Why not a wireless bridge?
 
Yes, as I mentioned in the OP, RF would be an option too.  I suppose even an IR-blaster type "air gap" would work.  However, for the moment, I'm just trying to see how viable a fiber optic link would or wouldn't be.  Some of the fiber optic cabling looks to be quite inexpensive.
 
NeverDie said:
I know I said ethernet, but looking into the pricing just now and seeing the two strands, it seems like it would be almost trivially easy to do serial io over it  using, say, an arduino, provided the rx/tx hardware was also easy to hookup. 
 
Transmitting data over optical fiber reliably is a lot trickier than you might think. You really don't want to try and do it down at the optical interface level.  Your best bet would be to purchase an optical converter designed for whatever protocol you want to use - ethernet, RS-232, RS-485, etc and deal with things on the copper side.
 
NeverDie said:
Yes, as I mentioned in the OP, RF would be an option too.  I suppose even an IR-blaster type "air gap" would work.  However, for the moment, I'm just trying to see how viable a fiber optic link would or wouldn't be.  Some of the fiber optic cabling looks to be quite inexpensive.
 
Playing with fiber does sound fun, but a wireless bridge or an inline Ethernet surge protector are <$20.  Also you have to consider that if lightning damage does happen on the garage end you may have to replace that fiber converter.  Finally, it seems that the 24VAC transformer may be a better path for lightning to affect other devices in your electrical system than ethernet.  Each ethernet port on the switch/router has its own isolation transformer and differential transceiver, so while you may fry the port or router, it seems unlikely that a favorable current path would find its way out another port to other equipment.
 
I see that Sparkfun used to sell some fiber optic transmitter and receiver modules that worked at TTL levels and even had example Arduino code:
10204-05.jpg

https://www.sparkfun.com/products/retired/10204
However, they were "retired" and not replaced with anything.  They were made by Toshiba for a digital audio application, so I'm not sure if they were the same or different than TOSLINK.
 
I thought it would be easy  to cheaply procure gear that does very low data rates, but apparently not.  At higher prices I agree the alternatives make more sense.
 
Back
Top