fibre optic cable


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What are the min components I should be considering when I am offering ethernet (TCP/IP IEEE802.3) to long distances using Fibre optic cable? Similar way profibus to long distances for remote I/Os.
Two popular fiber optical cable types exist. These can be described as single mode and multimode. Tight buffered 62.5 multi-mode cables accommodate communication up to about two km. Single mode cables accommodate communication toward 20 km. Perhaps the bandwidth could affect the specific distance limitations.

Whichever distance is applicable, you require the media converters for that type commucation medium, either single or multi-mode. Most of my applications use Ethernet. Similar converters exist for TIA 485, etc. via Black Box, Siemens, Hirschmann, Phoenix... These are among the industrial suppliers; not the outfits that I would purchase for my home applications.

From my experience with Siemens products, I can generalise the following.

The selection of required hardware components depends on:

1. Do you want to have a mix of electrical and optical cables? If yes, then you need modules to carry out electrical to optical and vice versa.
These are generally referred as Optical link modules.

2. You have to take care of the type of optical fibre you propose to use glass or plastic. Because the fibre can operate at different wavelengths that means once again you have to select the conversion modules supporting the selected wavelength.

Additionally you have to do a power budget calculation. simply put you have to do the following:

You take the minimum output power of the transmitter and from it subtract the minium input power required by the receiver for proper functioning. This difference will give you a value which is the maximum permissible amount of power loss you can have in the transmission medium and connectors. It is advisable to have losses upto a maximum of 80 percent from this maximum value to ensure proper functioning of the network.