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5.4.3 Serial Channel Interface
The serial interface is identical for all serial channels. The card supports software configurable RS-232/422/485
interfaces. The termination for the RS-485 interface can be controlled via software. The serial I/O are protected
per IEC-61000-4 for ESD, surge and EFD. See section 2.0 for specification details.
5.4.4 Isolation and Grounding
A "chassis ground" is provided on the printed circuit board for EMC and ESD performance. It is accessible via
the four mounting holes at the front, as shown in the figure below, and may be connected to a metal enclosure
or mounting plate with appropriate conductive hardware. The two mounting holes at the back of the card are
isolated. As the card is not intended for use with primary circuits or other hazardous voltages, the chassis
node is a functional earthing point and is not intended as a protective earth (PE) terminal. The mounting holes
are thermally connected to the board's power and ground planes and intended as a means to extract heat
from the board.
Reference (REF) lines are provided with each copper port and may be used as shield reference connections
for shielded twisted pair (STP) cabling. Typically, unshielded twisted pair (UTP) cabling should be used, such
as Cat 5e. If STP cabling is required, shields may need to be terminated and connected to the enclosure entry
point. Note that the REF lines are connected to chassis through a parallel capacitor and 10 MΩ bleed resistor.
This card is intended for use with SELV rated power supplies and Ethernet Environment A, as defined by IEEE
802.3 section 27.5.3. Extension of copper Ethernet segments that cross Environment B boundaries may
require additional isolation. Note that VIN+ and VIN- are isolated from chassis.
Focal Technologies Corporation
A Moog Inc. Company
MOUNTING HOLES
MOUNTING HOLES
Figure 5-7: Mounting Holes Locations
Model 922-DSLH – User Manual
Document No. 922-0677-00, Rev 1.0
Page 5-8
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