Toshiba VF-A7 - Manual (Page 16)

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4. Grounding
Grounding is of particular importance for reliable, stable operation. Communication
system characteristics may vary from system to system, depending on the system
environment and grounding method used. The ETH-100 interface is provided with a
“GND” screw terminal on the bottom of the unit. This “GND” terminal constitutes an
effective “chassis ground”, and is directly connected to the metallic housing of the
shielded RJ45 Ethernet network connector and to the appropriate locations on its
integrated isolation magnetics.
This chassis ground plane is physically separate from the ETH-100’s control logic
ground plane, which is directly referenced to the CC (control common) terminal on
the connected drives. Switch SW1 #2 on the ETH-100 unit, however, provides a
method to selectively connect these 2 ground planes together.
When switch SW1 #2 is ON (switch in the “down” position when looking at the bottom
of the ETH-100 unit end-on), the ETH-100’s control logic ground plane and chassis
ground plane are connected together. In this configuration, no external GND wire
should be connected to the unit’s GND terminal. In this case, the chassis ground
plane is directly connected to the drives’ CC reference, and Toshiba typically
recommends that the CC reference of the drives not be connected to earth ground.
Refer to your drive’s instruction manual for specific information about the CC terminal
and ground connections.
In some high-noise environments or under unusual wiring conditions, it may be
possible to obtain improved Ethernet communication characteristics by referencing
the ETH-100’s “chassis ground” to a localized earth ground. In these cases, place
switch SW1 #2 in the OFF (up) position and connect the GND screw terminal to an
appropriate ground connection.
Please be sure to consider the following general points for making proper ground
connections:
Grounding method checkpoints
1. Make all ground connections such that no ground current flows through the case
or heatsink of a connected drive.
2. Do not connect the ETH-100’s GND terminal to a power ground or any other
potential noise-producing ground connection (such as a drive’s “E” terminal).
3. Do not make connections to unstable grounds (paint-coated screw heads,
grounds that are subjected to inductive noise, etc.)