Siemens SIMATIC NET PROFIBUS manual Setting the Terminating Resistor

Infrared Link Modul (ILM) 6ZB530–3AC30–0BA1

6.1Setting the Terminating Resistor

Electrical cables in a PROFIBUS network must be terminated with the characteristic impedance of the cable at the start and end of the bus. Switch S202 is used for this purpose on the basic module of the PROFIBUS ILM.

Note

Note that the switch must be set to “terminating resistor activated” if a PROFIBUS ILM is located at the start or end of an electrical PROFIBUS network (only one PROFIBUS cable connected).

The switch must be set to “terminating resistor deactivated” if a PROFIBUS ILM is looped into a PROFIBUS network (two PROFIBUS cables connected).

If the terminating resistor is not set correctly, sporadic errors will occur on PROFIBUS that cannot be detected by the PROFIBUS ILM.

SIEMENS SIEMENS

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Terminating resistor		Terminating resistor
off		on
Figure 7:	Setting the Terminating Resistor

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