No RJ-45 Link Established

I am experiencing a strange problem that seems to be originating in my hardware, but I am looking to understand what condition could cause this behavior.

I am using Anybus CompactCom M40 both PROFINET and EtherNet/IP, and while everything appears to start up properly and the device is communicating with my host application, the RJ-45 port never establishes a link to my PC or network. This is only happening on one specific host device. I can use the same ethernet cable and same Anybus module on a different identical host device and everything connects to the network properly, but no matter how many different Anybus modules I try with the troublesome device, none of them link to my network.

Is there any condition that would prevent the Anybus module from linking to the network even if everything else appears to be working properly?


Do the LED on the CompactCom show any activity?

What is the host device that is causing the problems?


I just wanted to follow up on this issue in case anyone experiences the same in the future. We determined that an incorrect component substitution had been made on our device resulting in the supply voltage being 2.5V instead of 3.3V. This was enough to make it appear everything was powered up properly, but wasn’t enough to run the network connection.

Thank you for the update.