PLC Recovery & Diagnostics
Navigating connectivity challenges is a reality when working with Micro800 series PLCs.
While many issues are solved over the network, certain configuration errors require reverting to serial-based recovery. This guide focuses on common Ethernet pitfalls, such as DHCP conflicts and IP misconfiguration, and how to utilize your serial connection as a final troubleshooting resort.
1. Continue with Downloading of Ethernet Settings Prompt
When creating a new project in Connected Components Workbench (CCW) and adding a PLC, the project defaults to DHCP. If you download this program without manually setting your Ethernet IP address settings in the project, you will encounter a prompt asking if you want to proceed. Clicking "Yes" will revert your PLC’s Ethernet settings back to DHCP. Always ensure your IP settings are statically defined within your CCW program before downloading to avoid losing your established connection.
2. Resolving Random IP Addresses (169.254.X.X)
If your PLC is assigned an IP address in the 169.254.X.X range, it indicates that DHCP is enabled but no DHCP server is available to assign an address. Consequently, the PLC assigns itself an APIPA address. This frequently occurs even if you previously assigned a static IP. If you create a new project in CCW without setting the IP address to static, the next download will overwrite your previous configuration, reverting the PLC to DHCP. To resolve this, ensure your project explicitly defines a static IP address.
3. Recovering from an Invalid IP (0.0.0.0)
Accidentally writing "0.0.0.0" to a Micro820 IP address will result in the loss of all Ethernet communication. Because the Ethernet port becomes unresponsive, you cannot fix this through the network. You must restore communication by connecting to the PLC via its serial port.
4. Establishing Serial Connections as a Last Resort
When Ethernet is unavailable or misconfigured, connecting via the serial port—or a USB-to-serial adapter—is your primary recovery path. Ensure your cable is securely seated and that you have selected the correct COM port in your communication software to regain access to the PLC’s configuration settings.