Siemens SIMATIC NET PROFIBUS manual Measuring sockets, Function not guaranteed

8 Appendix 8.4 Measuring sockets

8.4 Measuring sockets

Signal quality

good

Normal operation

critical

Reduced optical system reserves

poor

Function not guaranteed

0 100 200 300 400 500 600 700 800 900

Output voltage [mV]

Diagram 1: Assignment of measured output voltage to signal quality.

Notes:

In order to attain a valid reading, it is necessary for the partner OLM at the other end of the optical fiber to send regular PROFIBUS frames. This can be seen on the LED display of the partner OLM (see 5, ”LED Indicators and Troubleshooting“, p. 25).

The output voltage at the measuring sockets is subject to many influencing factors, such as:

the strength of the transmitting power of the partner OLM

the ambient temperature of the optical sender and receiver

attenuation of the transmitting link

the transfer rates being used

The measuring sockets are therefore not intended as a substitute for a calibrated level measuring device with a calibrated light source.

The readings taken should only serve to classify the optical signal being received in the 3 classes

 good		(normal operation)
	critical	(reduced optical system reserves)
	poor	(function not guaranteed)

Measurements must be taken with a conventional ungrounded and high-resistance voltmeter. A connection to the OLM housing is not permitted either from the measuring sockets or the reference potential.

Version 1.0 8/00 35