Hi everyone,

Its my first time with Fiber Optic Profibus

I'm using OLM/G12 V4.0 which allows 9,6 kbit/s - 12 Mbit/s range for transmission rate.

Could anyone help me to know if there is any other limitations to set the network transmission rate (according to FO cable length or what else ..) ? And how do I estimate the appropriate one ?

Thank You

Hello Amen;

When you discuss distance versus data speed for Profibus you are discussing RS-485 (copper) caracteristics.

When you are looking at fiber-optic transmission the distance allowed depends on the type of fiber and corresponding model of OLM you are using: plastic or PCF fiber for OLM Pxx models, silica glass for OLM Gxx models (with variations due to multimode or single-mode fiber and optical wavelength). Look at the table in attachment below, taken from this manual:

SIMATIC NET PROFIBUS, Optical Link Module - Siemens

You need to allow for the data rate only when you want to calculate Profibus parameters for specific topologies, such as redundant rings. In linear bus and star topologies (on the optical line)  your Profibus cnfigurator takes care of these parameter values, as long as you insert the number and type of OLMs in your configuration.

Study this document for more details on the subject.

How do you set the PROFIBUS bus parameters when using OLMs in STEP 7?

Hope this helps,

Daniel Chartier

I'm so grateful for your support Daniel.

It is a kind of you

Hello Amen Allah ,

I will add some points regarding your Profibus network :

- define your OLMs topology and configure the Dip Switches , refer to this manual for more details.

- It's relevant use an active bus termination in the copper side .

- Respect the limitation per segment

- The proper installation is very relevant

-....

Regards