Error 701-8004250A.Failed to go online with controller. Unable to Open connection

Problem Faced:
• We are unable to connect with CPU via Rslogix 5000
• Whenever we try connecting we receive an error “Error 701-8004250A.Failed to go online with controller. Unable to Open connection—All connections may be in use”. Please refer the below image

• Everything was fine till few days ago & we are able to go online.
• Attached is the overall system Topology for your reference.( system Topology.pdf)
• Please refer below the screen shoots taken using Logix5000 task monitor utility. Apparently we have 262 available connections & we are not using more than 40 .Additionally CPU utilization also seems reasonable around 13 %,

Controlnet CPU usage is 100 %

• Furthermore when we browse Rslinx, we cannot see the secondary CPU. Please refer the below image

• When we are trying to upload from RSnetworx, we cannot see secondary CPU & the error code CNET:8222 is appearing. Please refer the attached snapshots

• System Overhead slice time is currently at 20%
NUT is 5msec & RPI is 40msec
• We are able to receive data in DCS & all IOs are also OK. Both CPUs are synched & all LEDs are OK (all Solid Green) but we are not able to go online with the CPU.

Did you try going online using other computer?

Yes I did from 3 other computers but the response is same.I also remove all HARMONY files, delete ETH driver. Restart PC & configure it again, But to no use.

I cannot even see the Secondary controller in Rslinx. Please refer the attached image.

receive data in DCS

Click to expand...

What DCS ? Does it connect via ControlNet, Ethernet, or Modbus ?

The 100% CPU usage on the ControlNet module is almost certainly the heart of the problem. Figure out what's slamming the ControlNet and you may be able to free up enough resources to get online via the ControlNet network and bridge modules.

I just restarted the Secondary CPU.Everything get fixed & i am able to access CPU.