I have build up two fiber rings with Scalance XC206-2.

Ring 1 = 26 switches
Ring 2 = 13 switches

One switch in each ring is MRP Master and rest is client. I have defined port 7 and 8 to be the redundancy fiber. To each switch in general has I connected a Siemens RIO.

I have no errors and everything is green in TIA portal.
The switches is configured in TIA portal V14 SP1 Update 5.

Network is stable and good, but when I try to make a fiber problem by disconnect a fiber cable the problems starts....

Example 1:
If I`m online and monitor a analog value, it goes to 0 and then jump back to normal value (mA on the input). for Ring 1 its 0 for approx. 7,5 seconds and for ring 2 0,5-1 second.

Example 2:
I have created a trace function in the PLC who active on OB1 (each scan), it also show the same....

I have tried to ping all the ip addresses on ring 2... and when I make a error, I cannot see any differences on the ping response....

From documentation the MRP shall quantity max 200ms down time if you have less then 50 switches or something ?

What can the problem be?

Please see attached screenshots of my topology.

Does anyone know how to solve this, I have the same problem.

Thanks

Dear mrvica,

had a similar problem yesterday an received the following, verified advice from siemens support.

The main reason is that the fiber redundance needs 200ms to update after fiber connection or fiber disconnection.

Tha HW Devices have usually much shorter default timeouts (watchdog timer/WT) of like 2x cycle clock with cycle clock being a few 1-4ms, dependent on the component.

This can be fixed by increasing the WT 100-fold with the following steps.

1. Select the HWComponent that has WT during fiber (dis)connection.

2. open the PN-IO.ObjectProperties.

3. increase the watchdog timer Factor from 2x to ~102x so the WT becomes slightly above 200ms.

4. save-compile-download HWConfig.

5. Done, see also attached screenshot.