Tecomat Foxtrot – system design
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Crossed cables
are used for direct connection of two equivalent devices (e.g. HUB - HUB (without
the uplink port on HUBs), Foxtrot - PC, Foxtrot - Foxtrot). They are not commonly available and they have
to be ordered with an expressed request for a crossed cable. The cable is fitted by the RJ-45 connectors
on both ends (8 pins).
Only 4 signals are functional (for commonly used 10Base-T interfaces), the other conductors are not
used (outlined by dashed lines on Figure 1.1.5.2). A cable with twisted pairs has to be used (a non-
twisted phone line cable must not be used!) and one twisted pair has to always be used for one data flow
direction.
The basic product line of crossed cables is supplied under the order number TXN 102 06.xx (the numbers
behind the point specify the cable length according to the product line - see the TC700 catalogue).
TD+
1
1 TD+
TD–
2
2 TD–
RJ-45
RJ-45
KONEKTOR
KONEKTOR
ETHERNET
ETHERNET
RD+
3
RD–
6
3 RD+
6 RD–
–
4
–
7
–
5
–
8
4 –
7 –
5 –
8 –
Figure 1.1.5.2 Connection of crossed TP cable ETHERNET
1.1.5.3.
Recommended UTP (FTP) cables for ETHERNET
TP cables (twisted pair) can be used as non-shielded (UTP) or shielded (FTP). The FTP shielded cables
can be very well used also for RS-485 distribution (see chapter 1.1.3).
UTP cables, recommended types:
PCEY 4x2x0,5 (PCEY 4x2x0,6), manufacturer VUKI a. s. (distributor ISOKAB s.r.o.)
UTP data cable – class 5, manufacturer KABLO ELEKTRO, a. s. Vrchlabí
UTP Cat. 5, manufacturer PRAKAB
FTP cables, recommended types:
PCEHY 4x2x0,5 (PCEHY 4x2x0,6), manufacturer VUKI a. s. (distributor ISOKAB s.r.o.), refer to chapter
3.6.2.
FTP data cable – class 5, manufacturer KABLO ELEKTRO, a. s. Vrchlabí
UNITRONIC EtherLine-H CAT. 5, manufacturer LAPP KABEL
FTP Cat. 5, manufacturer PRAKAB
1.1.5.4.
Principles of installation for ETHERNET distribution
General principles for installation of UTP cables:
When installing cables, sharp bends must be avoided. The cable should not be broken in corners, the
manufacturer specifies a minimum bending radius for each cable type – typically, the bending radius is six
times the diameter of the cable as minimum. Do nod bend the cable more than 90 degrees.
The cables must not be exposed to mechanical pressures. When drawing cables through holes or bars,
the permissible tensile strength must not be exceeded. Pulling the cables by excessive power more than
10 kg causes their damage by expansion of their twisting, which leads to failures (a higher error rate)!
The cables have to be mechanically protected, do not tense them, they should be left free. Also frequent
movements damage the cables.
If these principals of cable laying are not followed, data transmission could be slowed down and the cable
line could be interrupted. With respect to high frequencies, yet a small change to the geometrical
arrangement of the wires in the cable can cause data throughput problems (even if the cable can be
ohmicly in good order). The transitions of the cable to the connector are especially sensitive to mechanical
damage. In such cases, the cable can be protected from forced bending by axial tension.
RJ-45
ETHERNET
CONNECTOR
RJ-45
ETHERNET
CONNECTOR
