Hardware manual

PCI VELOCITY / OPTO ISO RS422/485 Specifications
Chapter 2 Page 7
Optical Isolation.
The PCI Opto Iso RS422/485, as mentioned above is
identical in installation procedure to the PCI Velocity RS422/485.
In addition, it also has optical isolation circuitry on board that
allows protection of:
1500 Volts DC
± 1000 Volts AC
This isolation present on board also allows greater
protection from current surges, lightning strikes to both the card
itself and the PC, and also it improves noise immunity by isolating
the PC from the cards transmit ground.