Control Network Newsletter
Industrial Diagnostic Switch Simplifies Testing
Contemporary Controls' Skorpion Diagnostic Switch helped a machine builder improve machine integration and network troubleshooting.
A benefit of switched Ethernet technology is that the switch restricts directed messages to only those ports party to the communication by learning the MAC addresses of the devices. This improves overall network throughput by not burdening end stations with useless traffic. However, this feature makes protocol debugging difficult because a protocol analyzer tool attached to an unused port on the switch cannot observe any directed messages of interest.
To test the machine's network functionality, the machine builder had to turn off the Ethernet switch to clear its MAC Address table each time he moved the Ethernet cables to test different devices on the machine.
"Having to cycle power for each test is very time-consuming, plus it was a hassle," said the machine builder. "I wanted a test port that was easily accessible and versatile."
Replacing the Ethernet switch with a Skorpion Diagnostic Switch met these requirements.
The Skorpion Diagnostic Switch retains all the features of an unmanaged switch, such as auto-negotiation and auto-MDIX, except for one significant feature—it does not learn. Because it does not update its database of source MAC addresses and switch port pairings, the Skorpion Diagnostic Switch continues to flood all ports with all messages—directed, multicast, broadcast—as if they were broadcast messages. This allows protocol tools, such as Wireshark®, to capture any network traffic that goes through the switch regardless of the port location of the traffic.
Instead of installing a managed switch with port-mirroring in each equipment room, the machine builder installed a Skorpion Diagnostic Switch in each control panel that had an Ethernet connected PLC Controller.
"Most of the traffic I was interested in was related to the PLC controller," said the machine builder.
The machine builder inserted the Skorpion Diagnostic Switch between the PLC controller and the IP network. Because the controller was located at the end of a single Ethernet drop, the Skorpion Diagnostic Switch acted as a three-port active tap with one connection to the PLC controller, one connection to the IP network, and one connection reserved for a protocol tool (such as Wireshark) running on a laptop. In fact, with this setup, the machine builder gained two additional spare ports.
"I don't need to leave my laptop connected," said the machine builder. "I just connect when I need to do protocol analysis, configure a device on-line, or observe web pages. With this set-up, I've gained a network diagnostic port ready at all times to be used."
The Skorpion Diagnostic Switch can be permanently installed on an installation or replaced with a plug-and-play unmanaged Skorpion switch once a system is commissioned. This device can also be useful when developing embedded Ethernet devices because you can connect the Skorpion Diagnostic Switch between two embedded Ethernet devices and view their messages using Wireshark.
Designed for the demanding requirements of an industrial automation environment, the Skorpion Diagnostic Switch can be used in control panel installations that require troubleshooting in the field. It can also be used in a development environment when debugging code.
Models are available that support gigabit speeds which minimize transfer time and improve the ability to stream high-bandwidth files to connected devices without interference.
To learn more, watch the Introduction to the Skorpion Diagnostic Switches video, or visit our Skorpion Diagnostic Switch product page.