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Reactive Power Controller
= Key 1
= Key 2
= Key 3
RS485 Interface (Option)
Transmission protocols
Two transmission protocols are available for the connec-
tion to an existing field bus system:
0 - Modbus RTU (Slave) and
1 - Profibus DP V0 (Slave) .
With Modbus protocol you can have access to the data of
table 1, and with Profibus protocol you can have access
to the data of table 2.
Bus structure
All devices are connected in bus structure (line). In one
segment up to 32 participiants can be assembled. At the
end and the beginning of each segment, the cable must
be terminated by resistors. In
Prophi
you can activate
these resistors with two plug-ins.
For more than 32 participiants you must use a repeater
(line amplifier) to connect the single segments.
Shielding
For connections via RS485 interface, you need a pro-
tected and twisted cable. To achieve a sufficient protec-
tion result, the shielding must be connected at both ends
extensively to the housing or parts of the cabinet.
Cable specifications
The maximum cable length depends on cable type and
transmission speed. We recommend cable type A.
Cable parameter
Type A
Typ B
Impedance
135-165Ohm
100-130Ohm
(f = 3-20MHz)
(f > 100kHz)
Capacity
< 30pF/m
< 60pF/m
Resistance
< 110 Ohm/km
-
Diameter
>= 0,34mm2
>= 0,22mm2
(AWG22)
(AWG24)
Cable length
The following table shows the maximum cable length in
meters (m) for various transmission speed
.
Baud rate (kbit/s)
Cable type
9.6
19.2
93.75 187.5 500
1500
Type A
1200 1200 1200 1000 400
200
Type B
1200 1200 1200 600
200
70
Terminal resistors
If
Prophi
is connected to the end of the bus cable, the
bus cable must be terminated at this point with resistors.
The required resistors are integrated within the
Prophi
and are activated in position ON.
Diagr. Connection RS485 interface
10200740
392R 221R 392R
23
22
21
A
B
+5V
OFF
ON
GND
GND
Termination
Prophi
