Specifications

Chapter 3 - Selecting RS-422 and RS-485 Cabling RS-422 And RS-485 Applications Ebook
Page 46 of 137 Manual Documentation Number: <DocNumber>
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approximately 100 kbps. As data rates rise beyond 100 kbps, cable
length drops off quickly. For example, at 200 kbps maximum cable
length is approximately 1600 feet. At 1 Mbps cable length should not
exceed approximately 200 feet.
Attenuation vs Frequency
Losses in a transmission line are a combination of AC losses (skin
effect), DC conductor loss, leakage, and AC losses in the dielectric. In
high quality cable, the conductor losses and the dielectric losses are on
the same order of magnitude. The following graph demonstrates the
significant difference in performance of different cables. This chart
shows attenuation versus frequency for three different Belden cables.
Note that the polyethylene cables offer much lower attenuation than
PVC cables.
Figure 33: Cable Attenuation vs Frequency