Siemens SIMATIC NET PROFIBUS - Manual (Page 380)

Infrared Link Modul (ILM) 6ZB530–3AC30–0BA1
38 Copyright

by Siemens
8.2 Connecting the Power Supply and the
Signaling Contact
Use a two-wire round cable if you do not want to use the signaling contact or a four-wire round cable if the
signaling contact is required. This is necessary so that the threaded cable inlet seals the cable entry and
prevents the cable from being pulled out. Ideally, you should use twisted pair cables since they are less
susceptible to noise. The outer diameter of the cables must be between 7.5 and 10 mm.
Do not connect power supply or signaling contact cables that are laid partly or completely outside buildings
without first providing a suitable surge voltage protector to protect the PROFIBUS ILM and your low-voltage
network. Otherwise, lightning strikes in the area can destroy the PROFIBUS ILM or other network components.
If the cable is laid outside buildings and in cable cable conduits along with cables supplying power, you should
also use a shielded cable for the power supply and signaling contact to prevent interference from the power
cables.
Connect the power supply and signaling contact cable to the terminal block as illustrated in Figure 17.
) – S1 S2
) – S1 S2
Terminal block
Cable clamp
Cable installed
Bare wire approx. 8 mm
Core insulation approx. 8 mm
Fold back braided shield
approx. 8 mm
Figure 17: Connecting the Power Supply and Signaling Contact Cable
If you have chosen a shielded cable, make sure that there is a good electrical connection between the braided
shield and shield clamp. This is guaranteed if you fold back the braided shield over the outer jacket of the
cable. This provides you with a sufficiently large cable diameter to clamp the cable.
Screw the threaded cable inlet so that if IP65 is required, the cable connection is watertight.
If this is required, PROFIBUS cables with a round cross-section and an outer diameter of 7.5 to 10 mm must
be connected.
Tighten the threaded cable inlet with a torque of approx. 2.5 to 3 Nm so that the collar of the threaded cable
inlet is sealed against the casing of the PROFIBUS ILM. When the cable is connected, the union nut of the
cable inlet must be tightened so that the cable can no longer be pulled out. When tightening the nut, make sure
that the cable does not turn with it.
If the power supply and signaling contact cable is subject to changing tensile stress, make sure that you
provide additional strain relief. The cable clamp in the device itself is only intended for low-resistance discharge
of spurious voltages on the shield. The threaded cable inlet is used only for sealing the cable entry and to
prevent the cable being pulled out accidentally. Neither of these, however, is intended as strain relief against
continuous tensile stress on the cables.