ABB Zenith ZTG 30 Operation, Maintenance And Installation Manual page 70

70
Z e n i t h Z T G S e r i e s AT S , O P E R AT I O N , M A I N T E N A N C E , A N D I N S TA L L AT I O N G U I D E
5.6.3.2 Termination resistor
The modules provide the possibility to
insert a 120 Ω termination resistor on
the CAN bus, by setting the DIP-switches
Rterm (1 and 2) on the side of the mod-
ules, in position ON. This option must
be selected before the installation of
the modules. With the Ekip Com Devi-
ceNet - modules, the dip-switches 3 and
4 of the Rpol (polarization resistance),
are not used.
ON IA
1 2 3 4
Rterm Rpol
120Ω
on
off
—
Fig. 5.19 Termination resistor; To enable the Rterm, the
dip-switches 1 and 2 must be positioned to ON. This option
must be selected before the installation of the module.
on
off
Notice
The termination resistors must never be in-
cluded in the nodes. The inclusion of this ca-
pability could easily lead to a network with im-
proper termination (impedance too high or
too low), potentially causing a failure. For ex-
ample the removal of a node, which includes a
termination resistor, could result in a network
failure. The termination resistors must not be
installed at the end of a branch (drop line),
only at the two ends of the main backbone
(trunk line).