Specifications

22 RS-422/485 Application Note
 Copyright B&B Electronics -- Revised October 1997
B&B Electronics -- PO Box 1040 -- Ottawa, IL 61350
PH [phone] -- FAX [phone]
Figure 3.2
Another approach to choosing transmission line is the “E-GRADE
Program,” which has been established by Anixter Bros. Inc. Anixter is a
worldwide distributor of wiring system products. Under this program, Anixter
divides data interface cables into four categories as follows:
E-GRADE 1 LIMITED DISTANCE
E-GRADE 2 STANDARD DISTANCE
E-GRADE 3 EXTENDED DISTANCE
E-GRADE 4 MAXIMUM DISTANCE
Simple charts are used to help the user select the proper cable without any
technical understanding of the cable parameters. This program divides the
usage categories into EIA-232-D, EIA-422-A, and EIA-423-A. When using
this literature, use the EIA-422-A charts for choosing RS-485 cable.