Specifications

Chapter 4 - Transient Protection of RS-422 and RS-485 Systems RS-422 And RS-485 Applications Ebook
Page 55 of 137 Manual Documentation Number: <DocNumber>
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The second approach is to tie each of the grounds on a device together
(typically power ground and data ground) with a low impedance
connection.
Figure 39: RS-485 Device with Signal Ground connected to Chassis Ground
These two techniques lead us to the two basic methods of transient
protection.
Transient Protection using Isolation
Implementing transient protection can be a daunting task. An
understanding of isolation theory, coupled with information on isolation
devices, can be helpful in finding solutions.
Isolation Theory
The most universal approach to protecting against transients is to
galvanically isolate the data port from the host device circuitry. This