Norgren VS18 Series Valve Advantage - Manual (Page 53)

VS18/VS26 MAINTENANCE & INSTRUCTION BOOKLET
8.2.2 Profibus DP wiring
The bus line is specified in EN 50170 as line type A. It can be used as shown in the following
table. The table gives the bus parameters and line lengths of A and B type lines for comparison.
However it is recommended that only type A lines should be used, due to their expanded length
capabilities.
Line parameter
Parameter Line A Line B
Impedance in Ohm 135 to 165 100 to 130
Capacitance per unit length (pF/m) < 30 < 60
Loop resistance (Ohm/km) 110 -
Core diameter (mm) 0.64 > 0.53
Core cross section (mm2) > 0.34 > 0.22
Line lengths
Baud rate (kBit/s) 9.6 19.2 93.75 187.5 500 1‘500 12‘000
Line A (m) 1‘200 1‘200 1‘200 1‘000 400 200 100
Line B (m) 1‘200 1‘200 1‘200 600 200 - -
Calculating possible line lengths
The maximum admissible distance between two bus stations in each Profibus network can be
calculated as follows:
(NO_REP + 1) * Segment length
NO_REP = The maximum number of repeaters connected in series (depends on repeater type).
Example:
The repeater manufacturer’s specifications allow nine repeaters to be connected in
series. The maximum distance between two bus stations at a data transfer rate of 1’500 kBit/s is
then as follows:
(9 + 1) * 200 m = 2’000 m
VS2672926-KG00E_05/07 Page 53/97