EtherNet/IP networks are highly reliable, providing the communications needed for 24/7-production facilities. Failures are rare, but because of the wise-spread nature of networks, they can be a challenge to troubleshoot. Network failures are frequently discovered while troubleshooting a controller problem. For example, the operator complains that a motor is not running at the correct speed. The troubleshooter determines the motor speed setpoint has not be received from another controller and suspects a network problem.

There are three general symptoms of a communications network failure:

• Data is transferred with errors
• Data transfer is intermittent
• Data is not being transferred