Rockwell Automation 1786-series ControlNet Fiber Media Planning and Installation Guide - Manual (Page 35)

Rockwell Automation Publication CNET-IN001C-EN-P - October 2011 35
Topology and Signal Considerations Chapter 2
1786-RPFRXL/B (Fiber Ring or Point-to-Point) Module
The 1786-RPFRXL (0…20 km) module is designed to solve extra-long distance
applications that require up to 20,000 m (65,620 ft) for single-mode fiber
between two ControlNet network devices. You must terminate extra long-
distance cable in the field.
The maximum length of a section is dependent on the quality of the fiber,
number of splices, and the number of connectors. The total attenuation for a
cable section must be less than 10.5 dB. This applies to single- or
multi-mode fiber.
62.5/125 Micron multi-mode OM1 Fiber
Use 62.5/125 micron cable with the 1786-RPFM, 1786-RPFRL/B, and
1786-RPFRXL/B modules for extra-long distance applications. The OM1 cable
is a graded index multi-mode type of fiber cable.
9/125 Micron single-mode OS1 Fiber
Use 9/125 micron with the 1786-RPFRXL/B module to achieve distances of up
to 20 km. The OS1 cable is a graded index single-mode type of fiber cable.
Determine Attenuation
Levels You must calculate the power budget for you fiber cable. The short-distance fiber
cable is pre-terminated; therefore the maximum attenuation level is 4.2 dB.
Once you start modifying the lengths of the segment, installing bulkhead or
fusion splices, installing longer distances, exposing the cable to temperature
ranges, or employing different quality cable and connector types, you must
determine your attenuation levels. The following examples provide you with a
place to start when you begin to determine your attenuation levels.
Attenuation Levels for a Short-distance Fiber Segment
The fiber cabling path loss can be verified by using the appropriate field test
equipment. You must test the cable using the same wavelength as the specific fiber
module in use.
The power budget for the short-distance fiber repeater module is 4.2 dB. This
means that the maximum amount of attenuation between the two repeater
modules shall not exceed 4.2 dB. This power budget is valid throughout the
operating temperature range (0…60 C° (140 °F)).