Troubleshooting Communication Issues with SLC 5/05 PLC: Tips for Connecting Without Knowing Communication Settings

Question:

Hello, I am having trouble establishing communication with my SLC 5/05 PLC, which has both RS-232 and Ethernet ports. Despite trying to monitor traffic with Wireshark in promiscuous mode, I did not observe any activity from the PLC's Ethernet port. The ENET LED on the PLC is on, but the RJ45 port LEDs show no activity. I also attempted to connect using DF-1 through RSLinx, trying various configurations such as CRC and BCC error checking, as well as adjusting the station number, but was unsuccessful. Is there a simple way to connect to the PLC if I am unsure of the communication settings? If a factory reset is possible to clear any existing program, that would be ideal. Thank you.

Top Replies

If you're struggling to connect online due to unknown communication settings, there is a simple solution. By removing the memory backup battery and shorting the GND and VBB terminals on the controller board for 60 seconds, you can reset the device to its factory default settings. This process will erase the memory and restore the communication settings to their original configuration. No need to worry about the program inside the device – this method will do the trick. Thanks for the question!

Thank you so much, Bit_Bucket! Wishing you all the best with your coffee and coding endeavors. Good luck!

Hi there! That sure sounds frustrating. A possible reason for your difficulties could be that the PLC's communication settings don't match with those you're using. Before resorting to a factory reset, I'd suggest you try using a null-modem cable with your RS-232 port, if you haven't already, and an Auto-configure feature in RSLinx if it's available. Sometimes this method can successfully establish a connection if the protocols, data bits, and stop bits align correctly. Do remember to also check the baud rate and parity too. Lastly, don't forget to check your IP address if you're connecting via Ethernet - you might need to ensure that your computer is in the same subnet as your PLC.

Hi there! Sounds like quite the communication quandary you're dealing with. Have you checked if there's a possible hardware issue with your Ethernet cable or RS-232 port? Sometimes it's the simplest things that cause headaches! Regarding factory reset, many PLCs do have this option, but be aware that it could wipe out all settings, which may or not be what you want. You didn't mention which software you're using for programming, but typically there's an "Auto-Configure" function to automatically detect your PLC's settings. This could save you the trouble of manually trying different configurations. Remember, direct communication is often the simplest and most reliable.

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Frequently Asked Questions (FAQ)

FAQ: 1. How can I troubleshoot communication issues with my SLC 5/05 PLC when I am unsure of the communication settings?

Answer: Answer: One approach is to attempt a factory reset on the PLC to clear any existing settings and programs. This can help in establishing a new connection without the need for specific communication settings.

FAQ: 2. What are some common methods to connect to a SLC 5/05 PLC without knowing the communication settings?

Answer: Answer: You can try using tools like Wireshark to monitor network traffic and observe any activity from the PLC's Ethernet port. Additionally, attempting to connect through RSLinx using DF-1 protocol with different configurations such as CRC and BCC error checking, and adjusting the station number, may help establish a connection.

FAQ: 3. How do I know if my SLC 5/05 PLC is properly connected when the ENET LED is on but there is no activity shown on the RJ45 port LEDs?

Answer: Answer: If the ENET LED is on but there is no activity on the RJ45 port LEDs, it indicates that the PLC is powered and Ethernet is enabled, but there may be issues with the network configuration or communication settings that need to be addressed to establish a successful connection.

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