Looking for Fiber Recommendations

We have a customer with RS-485 communications wiring running through underground ductbank. The shielded twisted pair wiring is connecting a Dell laptop in the managers office and running LookoutDirect to a DCM on a DL-250 PLC.

The ductbank has been in place for over ten years, and has a tendency to get water in it. This seems to be playing heck with our serial communications. They have some spare multi-mode fiber running between the two buildings, and have asked us to convert to using the fiber optic link.

We are looking at two options:

1) Replace the DCM with a fiber Ethernet card in the PLC, H2-ECOM-F. We would then use a commercial (office grade) ethernet CAT-5 to fiber converter. The concern here is how much of a headache we'll have changing the DirecNet driver to Ethernet in the Lookout.

2) Use a fiber modem on each end and transmitt the data using serial communications on the fiber.

I am looking for recommendations on the best approach, suggestions for making the transition painless, and any suggestions on hardware.

Thanks,

Tom

I have used phoenix contact media converters with good luck. You don't necessarily need to add an ethernet card in the plc or change any other system hardware. You can convert RS-485 to fiber and back again thus keeping your existing system intact.


EDIT:
In retrospect, I used it to convert cat 5 to fiber and then back. I checked their web site and they dont have anything for RS-485

http://www.telebyteusa.com/catalog/products/showcase/Fiber_Optic_485.htm

good stuff

Siemens have an Optical Bus Terminal (OBT) which just drops into a Profibus RS485 line. Unfortunately, I can't see from the specs whether it would work happily with non-Siemens' protocols, but no-doubt the Siemens salesman could clear up on that point. Part no. is 6GK1500-3AA00 and list price in Europe is ~ 200€.