
1.CONNECTING THE PROFIBUS FUNCTIONS CONNECTION B-63994EN/02
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1.4 TERMINATING RESISTOR
Each end of the bus cable must be terminated with a resistor as shown
below.
Ru=390Ω, 1/4W
Rt=220Ω, 1/4W
Rd=390Ω, 1/4W
VP(6)
RxD/TxD(+)(3)
RxD/TxD(-)(8)
DGND(5)
Since the connector manufactured by Phoenix Contact or Siemens
include the terminators above, the switch on the connector can be used
to enable or disable the terminators. In a configuration as shown
below, turn on the switches of the connectors for stations #3 and #6.
To supply power to the terminating resistors, the power to the unit at
each end of the cable must be turned on at all times during
communication. (In the example shown below, the power to units #3
and #6 must be turned on at all times during communication.)
#3 #7 #4 #5 #1 #6