RabbitLink EG2110 User Manual - page 33
User’s Manual
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C.2.2 Ethernet Port
The 10 Mbps twisted-pair Ethernet system allows segment lengths of approximately 100 m for
voice-grade twisted-pair telephone wiring. The maximum segment length may be shorter or longer
than this, depending on the quality of the twisted-pair cabling in your system. While the 10Base-T
system is designed to use voice-grade telephone cable, higher quality Category 5 cables, connec-
tors, and wire terminating devices provide the best possible signal carrying system for 100 Mbps
Ethernet media systems.
The 10Base-T media system uses two pairs of wires. They are terminated in an 8-pin (RJ-45 style)
connector. Four pins of the 8-pin connector are used as shown in Figure C.1.1-1. The transmit and
receive data signals on each pair of a 10Base-T segment are polarized, with one wire of each signal
pair carrying the positive (+) signal, and the other carrying the negative (-) signal.
C.3 Memory
The RabbitLink has SRAM and flash memory devices. The Dynamic C BIOS handles different
standard RAM and flash memory sizes automatically.
C.3.1 SRAM
The RabbitLink is designed to accept 128K or 512K of SRAM packaged in an SOIC case. It comes
standard with 128K of SRAM. Figure C.3.1-1 shows the locations and the jumper settings for the
jumpers at JP4 used to set the SRAM size. The jumpers are 0
Ω
surface-mount resistors.
Figure C.3.1-1 RabbitLink Jumper Settings for SRAM and Flash EPROM Size
SRAM
128K
512K
3
2
1
JP4
FD
JP4
SRAM
3
2
1
JP3
JP3
128K/256K
512K
Flash Memory
FD
JP2
JP2
128K/256K
512K
Flash Memory
FD
3 2 1
3 2 1
3 2 1
3 2 1
FD Factory
Default
Flash
EPROM
Flash
EPROM