D301144 0509
Installation PB-XEPI
19
Bus terminating resistors
Terminations of a PROFIBUS network must each be terminated with a bus terminating
resistor. Use standardized plugs containing terminating resistors.
.
Fig. 6: Bus termination configuration for PROFIBUS (see PROFIBUS standard IEC
61185)
Setting PROFIBUS parameters
Depending on the application software (not included in the scope of delivery) used, the
device can be a passive station (without an own station address) or an active station
(class 2 PROFIBUS master).
The setting of the PROFIBUS parameters is only required, if you use the device as a
class 2 PROFIBUS master or in the operation mode PROFIBUS network access. The
PROFIBUS parameters are given by the class 1 PROFIBUS master.
1 390
Ω
Pull-up resistance from pin 3 to positive supply voltage at pin 6
2 220
Ω
Cable terminating resistor between pin 3 and pin 8
3 390
Ω
Pull-down resistance from pin 8 to data reference potential at pin 5
Warning
The PROFIBUS is shorted if you use the device as a passive terminating
resistor (supply voltage from the device) and the device is switched off. This
may cause disruption or complete failure of PROFIBUS communication.
Use active resistors to avoid this problem. In this case the terminating re-
sistors are fed with +5 V and GND independently from the device.
+5 V DC/DC
(Pin 6)
Data+
(Pin 3)
Data–
(Pin 8)
GND
DC/DC
(Pin 5)
[2]
[3]
[1]
Bus terminating resistors
