Promag 53 PROFIBUS-DP/-PA 4 Wiring
Endress+Hauser 45
4Wiring
Warning:
• When connecting Ex-certified devices, see the notes and diagrams in the Ex-specific
supplement to this Operating Instruction. Please do not hesitate to contact your E+H
representative if you have any questions.
• If you use remote versions, connect each sensor only to the transmitter having the
same serial number. Measuring errors can occur if the devices are not connected in
this way.
4.1 Cable specifications for PROFIBUS-DP/-PA
4.1.1 PROFIBUS-DP: Cable specifications
Two types of cable are specified for the bus in the EN 50 170 standard. Cable type A
can be used for all transmission rates up to 12 Mbit/s. The cable parameters can be
taken from the following table:
When setting up the bus, observe the following points:
• The maximum cable length (segment length) of a PROFIBUS-DP system depends on
the transmission rate. With PROFIBUS-RS 485 Cable Type A, this value is:
• A maximum of 32 stations are permitted per segment.
• Each segment is terminated at both ends with a terminating resistor.
• The bus length or number of users can be increased by installing a repeater.
• The first and last segments can support a max. of 31 devices. The segments between
repeaters can support a max. of 30 stations.
• The maximum distance achievable between two bus users is calculated as:
(NUM_REP + 1) x segment length
NUM_REP = maximum number of repeaters, which can be placed in series, depend-
ent on the respective repeater.
Example:
According to the manufacturer's information, a maximum of 9 repeaters may be
placed in series on a standard line.
The maximum distance between two bus users at a transmission rate of 1.5 MBit/s is
thus: (9 + 1) x 200 m = 2000 m
Cable Type A
Characteristic impedance 135... 165
Ω at a measurement frequency of 3...20 MHz
Cable capacitance <30 pF/m
Wire size >0.34 mm
2
, equals AWG 22
Cable type twisted pairs, 1 x 2, 2 x 2 or 1 x 4 conductors
Loop resistance 110
Ω/km
Signal attenuation max. 9 dB over the entire length of the line segment
Shielding Copper braided shield or braided shield and foil screen
Transmission Rate [kBit/s] 9.6...93.75 187.5 500 1500 300...12000
Cable length [m] 1200 1000 400 200 100
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