INSTALLING THE TRMIM-20R
Page 3-4
3.3 CABLING THE TRMIM-20R
Prior to connecting cables, check that the the pinout and maximum
cable lengths throughout the system conform to the requirements
described in Chapter 2, Installation Requirements/
Specifications.
Since the TRMIM-20R uses differential Manchester encoding, the
trunk coupling unit (TCU) and Ring-In/Ring-Out trunk ports are not
sensitive to signal polarity. If the (+) and (-) lines within a pair are
reversed, the network will still function properly. Operating in this
condition is not recommended and, when discovered, the cable
connections should be corrected according to the information provided
in Chapter 2, Installation Requirements/Specifications.
3.3.1 Lobe Cabling
The physical lobe connection (see Figure 3-3) from the TRMIM-20R to
the token ring station does not require the use of a crossover cable.
The TCU and token ring station connectors are wired such that the
transmit pair from the TRMIM-20R connects to the receive pair of the
station and the receive pair from the TRMIM-20R connects to the
transmit pair of the station. This provides the necessary signal
crossover or Null Modem Effect. The Type 3 Media Filter provides
impedance matching from the Type 3 (UTP) lobe cabling to the Type 1
(STP) interface provided with many token ring stations.
The twisted pair segment from the TRMIM-20R can be connected to
any Token Ring station.
Figure 3-3. UTP Connections
TX+
TX–
RX+
RX–
6
3
4
5
TCU Port
Token Ring Station
TX+
TX–
RX+
RX–
4
5
6
3
TYPE 3
MEDIA
FILTER
TX+
TX–
RX+
RX–
1
6
9
5
Lobe Cable
RJ-45
DB-9