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Electromagnetic Flowmeter
COPA-XE / MAG-XE
9.3.7 Suppplementary Information for
Connecting Profibus DP
A Profibus DP Protocol is available among others in the
converter for digital communication. The digital communication
utilizes the RS 485 Data Link.
Transmission format RS 485 Data Link
Transmission speed 9.6 to 1500 KBit/s
Protocol per EN 50170
Ident-No. 6666 HEX
Cyclical (output variables, see separate Data Link Description
for COPA/MAG-XE, Part No. D184B093U09)
Cable
A shielded and twisted data cable is recommended.
Max. cable length 1200 m (Cable Type A)
Characteristic impedance 135-165Ω
Max. 32 instruments on a single bus
Baudrate: 9.6-1500 kbit/s
Distributed capacitance <30 pF/m, loop resistance 110 Ω/km
Tap length max. 1 m.
Incoming and outgoing cables on the same terminals.
Bus Terminations for Profibus DP
Both ends of the bus must have bus terminations installed, see
Fig. 41. In addition to the bus termination resistor R2 per the
EIA-RS-485 Standard a resistor R1 (Pulldown) to the data
reference potential GND and a resistor R3 (Pullup) to the plus
supply voltage +VD are to be installed. These two resistors
assure that a defined idle potential exists on the bus when no
participant is transmitting (idle time between telegrams, the
so-called idle status).
For values see DIN 19245, Part 1 and Part 3.
For Cable Type A: R1 = 390 Ω, R2 = 220 Ω, R3 = 390 Ω
Terminal Function Reference
+VD
A
B
GND
VP
RxD/TxD-N
RxD/TxD-P
C DGND
Supply voltage +5V
Receive/send-data-N
Receive/send-data-P
Data reference potential M5V
Fig. 40 Communication Profibus DP
R1
R2
R3
Fig. 41 Bus Terminations for Profibus DP, when the Instrument
is Connected at the End of the Bus
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