Siemens SIMATIC NET PROFIBUS Mixing Plastic Fiber-Optic and PCF Fiber-Optic, Calculation Examples

Configuring Networks

Mixing Plastic Fiber-Optic and PCF Fiber-Optic

To make the best use of the different cable lengths, the plastic fiber-optic cables and PCF fiber-optic cables can be mixed.

For example, connection between distributed local DP slaves using plastic fiber-optic (distances t 50 m) and connection between DP master to the first DP slave of the bus topology with PCF fiber-optic (distance u 50 m).

3.2.4Calculating the Power Budget of Glass Fiber Optical Links with OLMs

Calculation Examples

The following work sheets show typical calculations of the power budget for SIMATIC NET PROFIBUS glass optical fibers, one with OLM/G11, OLM/G12 at a wavelength of 860 nm and one with OLM/G11-1300 and OLM/G12-1300 at a wavelength of 1300 nm.

Note

Please note that the information on fiber attenuation in the data sheets and type specifications of fiber-optic cables are based on measurements with narrow-band laser light sources exactly adapted to the wavelengths.

The LED transmission elements used in practice produce a wider band spectrum whose mid frequency deviates slightly from the measured wavelength.

You should therefore use the following attenuation values on all connections with SIMATIC NET multimode glass fiber-optic cable between SIMATIC NET PROFIBUS components:

3.5dB/km at 860 nm

1.0dB/km at 1310 nm

Note

The following distances between two OLMs must not be exceeded regardless of the optical power budget:

OLM/P11, OLM/P12	400 m
OLM/G11, OLM/G12, OLM/G12-EEC	3 km
OLM/G11-1300, OLM/G12-1300	15 km

3-18	PROFIBUS Networks SIMATIC NET
	6GK1970-5CA20-0AA1 Release 2 05/2000