Endress+Hauser PROline promag 53 Mode D'emploi page 33

PROline Promag 53 PROFIBUS-DP/-PA
Endress+Hauser
Cable specifications for PROFIBUS-DP
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:
Cable Type A
Characteristic impedance
Cable capacitance
Wire size
Cable type
Loop resistance
Signal attenuation
Shielding
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:
Transmission Rate [kBit/s]
Cable length [m]
• 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
135...165 Ω at a measurement frequency of 3...20 MHz
<30 pF/m
2
>0.34 mm , equals AWG 22
twisted pairs, 1 x 2, 2 x 2 or 1 x 4 conductors
110 Ω /km
max. 9 dB over the entire length of the line segment
Copper braided shield or braided shield and foil screen
9.6...93.75 187.5
1200 1000
<
500 1500 300...12000
400 200
0
100
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