Rockwell Automation 1786-series ControlNet Fiber Media Planning and Installation Guide - Manual (Page 33)

Rockwell Automation Publication CNET-IN001C-EN-P - October 2011 33
Topology and Signal Considerations Chapter 2
Estimate Cable Lengths The maximum length of a fiber cable section for the fiber-optic modules is
dependent on the quality of the fiber, number of splices, and the number of
connectors.
If your distance requirements are less than 300 m, you can use a short-distance
(single-mode) cable that comes pre-terminated for use with the 1786-RPFS fiber
module. If your distance requirements are greater than 300 m, you must use a
1786-RPFM, 1786-RPFRL/B, or 1786-RPFRXL/B fiber module and terminate
the cables in the field, or purchase pre-terminated cables from your supplier.
When estimating maximum cable length, take into account attenuation that
occurs along the entire fiber path. Attenuation refers to the loss of light power as
it passes through the cabling components.
Typically cable attenuation for multi-mode fiber at a wavelength of 1300 nm is
less than 1.5 dB/km, and connection losses are 1 dB per connection.
Each Rockwell Automation fiber system has different constraints; therefore
maximum fiber-optic cable lengths differ for each system. Rockwell Automation
offers four different systems that are targeted to solve different applications:
• 1786-RPFS: Short-distance fiber system
• 1786-RPFM: Medium-distance fiber system
• 1786-RPFRL/B: Long-distance fiber system
• 1786-RPFRXL/B: Extra-long distance fiber system.
Table 5 - Fiber Module Distance and Ratings
Module Typical Repeater Distance (1) Cable Type Optical Power Budget Connector Type
1786-RPFS 0…300 m 200/230 micron, single-mode
650 nm 4.2 dB V-pin
1786-RPM 0…3 km 62.5/125 µm, multi-mode
1300 nm, graded index 13.3 dB ST (plastic or ceramic only; do
not use metal connectors)
1786-RPFRL/B 0…10 km 62.5/125 µm, multi-mode
1300 nm, graded index 15 dB
1786-RPFRXL/B 0…20 km 62.5/125 µm, multi-mode (2)
1300 nm, graded index
10.5 dB
9/125 µm, single-mode (3)
1300 nm
(1) Entire network limited to 20 km max, per ControlNet network specifications.
(2) Although you can use multi-mode cable with the 1786-RPFRXL/B module, it is not recommended because achieveable distance is limited to 6.6 km.
(3) Also compatible with 62.5/125 µm , multi-mode cable.
IMPORTANT Avoid lengthening your cable by joining sections with connectors.
Connectors can cause considerable attenuation and limit the maximum
length of your system. Be sure to check the attenuation of different cable
sections after the cable is installed.