Gantner e.bloxx A5CR, Руководство пользователя

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e.bloxx A5-1CR
MOUNTING e.bloxx AND CONNECTING WIRES
HB_EBLOXX-A5CR_E_V11.doc
17
Gantner Instruments Test & Measurement GMBH
Bus Connection to Profibus-DP
For the installation of the bus cable and bus interface, 9-channel D-subminiature plugs and sockets are used. The pin
assignment for the RS 485 connection according to PROFIBUS is shown in Table 3.1.
Plug Pin RS 485 Notation Signal Identification
1
5
6
9
DB 9
1
2
3
4
5
6
7
8
9 -
-
B / B´
-
C / C´
-
-
A / A´
- Shield
RP
RxD/TxD-P
CNTR-P
DGND
VP
RP
RxD/TxD-N
CNTR-N Shield, Protective Ground
Reserved for Power
Receive/Transmit-Data-P
Control-P
Data Ground
Voltage Plus
Reserved for Power
Receive/Transmit-Data-N
Control-N
Table 3.1. - Pin Assignment D-Subminiature Plug According to PROFIBUS
The signal leads A and B (and Shield) are mandatory for a (shielded) connection. Additional signal leads may be
installed if required.
Notice:
Due to the fact that the RS 485 interface is used for different protocols, in case of using Profibus-DP the
leads A and B has to be crossed.
Bus Termination at the e.bloxx Modules
In order to avoid signal reflections on the bus, each bus segment has to be terminated at its physical beginning and at
its end with the characteristic impedance. A terminating resistor is installed between the bus leads A and B for this
purpose. In addition, the bus lead A is connected via a pull-up resistor to potential (VP) and the bus lead B is connected
via a pull-down resistor to ground (DataGround). These resistors provide a defined quiescent potential in case there is
no data transmission on the bus. This quiescent potential is level high.
The e.bloxx modules have built in these bus termination resistors. They can be connect to the bus by plugging the Bus
Termination Plug IBT 100
, which is available as accessory, into the rapid bus link plug on the front side of the module.
Instead of the bus termination plug
IBT 100
, also separate jumpers may be used for the bus termination. In this case, it
is mandatory that the jumper clips are installed as indicated below, and that the bus leads or the bus termination are not
short-circuited by mistake.
R
A
A
U+
U+
B
B
U-
U-
R
R
R
R
R
d
d
t
t
u
u
Picture 3.9. - Bus Termination at the e.bloxx Modules