User`s manual

User’s Manual Hardware Reference 2–7
2.2.2 Ethernet Port
Figure 2–3 shows the pinout for the RJ-45 Ethernet
port (J4). Note that there are two standards for num-
bering the pins on this connector—the convention
used here, and numbering in reverse to that used
here.
The transformer/connector assembly ground is con-
nected to the RabbitCore RCM2100 printed circuit
board digital ground via a 0 Ω resistor “jumper,”
R5, as shown in Figure 2–4.
The factory default is for the 0 Ω resistor “jumper”
at R5 to be installed. In high-noise environments, it
may be useful to ground the transformer/connector
assembly directly through the chassis ground. This
will be especially helpful to minimize EMI prob-
lems. Once you have removed the 0 Ω resistor
“jumper,” R5, use a screw in the position indicated
in Figure 2–5 to attach the RabbitCore board to the
chassis ground,
thereby grounding the transformer/
connector assembly
.
The RCM2115 version of the RabbitCore has Ether-
net capabilities, but the transformer/connector
assembly and the ACT and LNK LEDs (shown to
the right of the transformer/connector assembly in
Figure 2–5 above) are not installed. The Ethernet
signals and the LED control signals are located on
header J3 on the bottom side of this version of the
RabbitCore, which may then be plugged in to the
rest of the system. An Ethernet transformer and
LEDs should be present on the board that the Rab-
bitCore RCM2115 version is plugged into.
Figure 2–3: RJ-45 Ethernet Port Pinout
Figure 2–4: Isolation Resistor R5
ETHERNET
RJ-45 Plug
1. E_Tx+
2. E_Tx
3. E_Rx+
6. E_Rx
1
8
RJ-45 Jack
RJ-45 Ethernet Plug
R5
Chassis
Ground
Board
Ground
Figure 2–5: R5 and Chassis Ground Locations