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5. 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.)