Siemens SIMATIC NET PROFIBUS Instrukcje Operacyjne Pobierz pdf (Strona 21)

Network Topologies

3.3 Ring Topology

SIMATIC NET PROFIBUS Optical Link Module OLM V4.0

Operating Instructions, 01/2013, C79000-G8976-C270-03

3. Fault, FOC2 interrupted:

OLM 1 OLM 2

SystemLED = lit green SystemLED = lit green

CH1/0 LED = lit yellow CH1/0 LED = lit yellow

CH2 LED = lit yellow CH2 LED = lit yellow

CH3 LED = lit red CH3 LED = lit red

2. The redundant optical ring consists of exactly two OLMs and both fiber-optic cable

connections are of exactly the same length.

Under these circumstances, that the receiving OLM receives a frame on both of the optical

channels at the same time. To manage this case, the OLM prioritizes the two optical

channels. By definition, the frame on one optical channel will then be taken as an echo

(channel LED = off) and the frame on the other optical channel will then be taken as a

forwarded frame (channel LED = yellow).

Due to the effect of jitter and the resulting sampling differences between the two optical input

channels, it is possible that one or the other optical channel receives a frame first. Due to the

extended display time of at least 300 ms. all channel LEDs are then lit yellow continuously.

 Configuration 1/2 (FOC1 = FOC2), LED display A:

1. Situation, no FOC interruption:

OLM 1 OLM 2

SystemLED = lit green SystemLED = lit green

CH1/0 LED = lit yellow CH1/0 LED = lit yellow

(continuous, flashing, flickering) (continuous, flashing, flickering)

CH2 LED = lit yellow CH2 LED = lit yellow

(continuous, flashing, flickering) (continuous, flashing, flickering)

CH3 LED = lit yellow CH3 LED = lit yellow

(continuous, flashing, flickering) (continuous, flashing, flickering)

2. Fault, FOC1 interrupted:

see above

3. Fault, FOC2 interrupted:

see above

Generally:

Regardless of whether a channel LED is lit or not, all optical channels are monitored

continuously in the redundant optical ring. If a channel LED is not lit, the frames circulating

on this channel are used to monitor the transmission line. The productive communication is

implemented over the channel with the LED lit yellow.

Without exception, faults are indicated by a red channel LED and by the signaling contact.

We recommend that you connect the signaling contact for safe monitoring of the OLM.

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