Festo CPX-FB13 - Connecting the Field Bus

1. Installation
1−17
Festo P.BE−CPX−FB13−EN en 0811c
1.3 Connecting the field bus
1.3.1 Field bus cable
Note
If installation has not been carried out correctly and if high
baud rates are used, data transmission errors may occur
as a result of signal reflections and attenuation.
Causes of the transmission faults can be:
 missing or incorrect terminating resistor
 incorrect screening/shield connection
 branches
 transmission over long distances
 unsuitable cables.
Observe the cable specifications.
Refer to your controller
manual for information on the type of cable to be used.
Note
If the CPX terminal is fitted onto the moving part of a
machine, the field bus cable on the moving part must be
provided with strain relief. Please also observe the relevant
regulations in EN60204 part 1.
Use a twisted screened 2−core cable for the field bus in
accordance with PROFIBUS specifications (EN
50170,
cabletype A):
surge impedance: 135 Ū 165  (3 Ū 20 MHz)
capacitance per unit length: < 30 nF/km
loop resistance: < 110 /km
core diameter: > 0.64 mm
core cross−sectional area:  0.34 mm
2
Bus length Exact specifications on the bus length can be found in the
next section and in the manuals for your control system.