Black Box ME475A-R2, Manual

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724-746-5500 | blackbox.com Page 16
Black Box Short Range Modem
3.2 FOUR-WIRE INSTALLATION
When communicating over a two twisted pair circuit, the ME475A-R2 can operate full
or half duplex, point-to-point or multipoint. In two pair point-to-point applications, you
will need a
pair of ME475A-R2s for each circuit—one at each end of the single pair
wire. In two pair multipoint applications you will need three or more ME475A-R2 units.
These can be connected using a star topology, although a daisy chain topology is usu-
ally used.
Four-Wire Cable Connection Via RJ-45
1. The RJ-45 jack on a ME475A-R2 Short Range Modem is pre-wired for a stan-
dard TELCO wiring environment. To be sure you have the right wiring, use the
table below as a guide.
†Connection to ground is optional
2. Proper crossing of pairs between the two modems is as follows:
RJ-45 Signal
1 ------------------ NC
2 ------------------ GND†
3 ------------------ RCV
4 ------------------ XMT
5 ------------------ XMT
6 ------------------ RCV
7 ------------------ GND
8 ------------------ NC
XMT XMT
XMT XMT
GND GND
To Shield (Optional)
}
One Pair