Chapter 4 Page 50 - Brainboxes CC-310 Hardware Manual

RS422/485 Information
Configuration A)
connected to protective ground, at one point only by a 100
resistor with a power dissipation rating of 1/2W. An
additional provision may be made for the resistor to be bypassed
with a strap to connect signal common and protective ground
directly together when specific installation conditions necessitate.
Configuration B)
directly to protective ground. The same configuration need not be
used at both ends of an interconnection; however, care should be
exercised to prevent establishment of ground loops carrying high
currents. (Note: Under certain ground conditions in configuration
A, above, high ground currents may cause the resistor to fail;
therefore, a provision should be made for inspection and
replacement of the resistor.)

Chapter 4 Page 50

PCI VELOCITY / OPTO ISO RS422/485
The circuit common of the equipment is
The circuit common shall be connected