Specifications

Chapter 3 - Selecting RS-422 and RS-485 Cabling RS-422 And RS-485 Applications Ebook
Page 47 of 137 Manual Documentation Number: <DocNumber>
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Note 1: Above attenuation data is supplied courtesy Belden Wire and Cable Company
Note 2: Datalene is a registered trademark of Belden Wire and Cable Company. Datalene is a type
of foamed cellular polyethylene insulation.
Using Cat 5 for RS-422/485
There are many cables available that meet the recommendations of
EIA-422 and EIA-485. Another choice is the cable used in Ethernet
network installations: Category 5 cable. Commonly referred to as "Cat
5" cable, its specifications are defined in the EIA/TIA/ANSI-568
specification. Because such a large volume of this cable is used, it is
relatively inexpensive, often less than half the price of specialty RS-
422/485 cabling. The cable has a maximum capacitance of 17 pF/ft
(14.5 pF/ft typical) and characteristic impedance of 100 ohms.
Figure 34: Category 5 Cable
Cat 5 cable is available as shielded twisted pair (STP) as well as
unshielded twisted pair (UTP) and generally exceeds the
recommendations for RS-422, making it an excellent choice for RS-422
and RS-485 systems.