Kipp&Zonen COMBILOG Data Logger - Manual (Page 93)

Only signal leads A and B (and Shield) are absolutely obligat-
ory for a (shielded) connection. All others can be installed to-
gether with these signal leads if required.
10.6 Bus Termination
In order to avoid signal reflections on the bus, each bus seg-
ment has to be blanked off at its physical beginning and at its
end with the characteristic impedance. For this purpose, a ter-
minating resistor Rt is installed between the bus leads A and B.
In addition to that the bus lead A is connected via a pull-down
resistor Rd to ground (Data Ground) and the bus lead B is con-
nected via a pull-up resistor Ru to potential (VP). These resist-
ors provide a defined quiescent potential in case there is no
data transmission on the bus. This quiescent potential is level
high.
Figure 10.5 Bus termination
Note: The numbers in brackets in figure 10.5 indicate the pin
number for the connection via the 9-channel D-sub miniature
plug.
Hardware Manual COMBILOG 1022
93
VP
DGND
Ru
Rt
Rd
VP = +5V
Ru = 390 Ω ± 2%, min ¼ Watt
Rd = 390 Ω ± 2%, min ¼ Watt
Rt = 390 Ω ± 2%, min ¼ Watt
B
A
B (3)
A (8)
Profibus-
Bezeichnung
Combilog-
Klemmen-
bezeichnung
watt
watt
watt
reference
reference