Hello

I have a problem with a Scalance X005 switch.

There is Siemens equipment connected via ethernet to the NCU - ​​MCP - PCU line, which is working properly. But I need to organize a star connection through the Scalance X005 switch. I connect NCU, MCP and PCU to it, but they do not see each other. The LEDs of the ports to which the MCP and PCU are connected are green, but sometimes go out for a fraction of a second. On the MCP itself, all the LEDs blink rhythmically, but on the PCU the network is not identified, not a single packet arrives and the NCU does not ping from it. On Scalance, the LED of the port to which the NCU is connected flashes green unevenly: it lights up for 1 second and goes out for 2-8 seconds. At the same time, the green blinking is not described in the manual for this switch at all. I have tried connecting a cable from the NCU to other ports on the switch, but their LEDs behave the same. Strange behavior given that this is an unmanaged switch.

Can you please tell me what could be the problem with this switch?

Hi lime76

It sounds like the NCU starts connecting to the switch and then disables its port and then tries again to establish connection and the disables the port again and then repeats the procedure.

Perhaps when the NCU/switch is trying to negotiate the speed, it fails to establish a correct speed?

Or, the ip of the NCU already exist and the NCUs response is to disable and try to connect again?

Have you tried to have only the NCU connected to the switch?

Have you tried to test with a different switch?

Regards

Hi lime76

I must admit that I do not know what your "NCU" is so I do not know why it would behave this way.

There could be some intelligence involved that makes it reset the port in case it does not find what it is looking for.

Best regards