Hello everyone, I am currently dealing with a customer who needs a CQM1H (CPU51) replaced. They sourced the processor as new-old-stock online and it arrived in its original packaging with a safety label intact, indicating it is in good condition. I acquired a secondhand power supply to use with the processor for programming on the bench. The customer provided me with an SD card containing the machine's project files, which I successfully loaded into CX-ONE on my Windows 7 computer. After some trial and error with communication settings, I managed to establish the correct protocol and connect my computer to the processor. However, I encountered some errors at the end of the transfer process. As a result, the PLC processor now constantly shows the ERR/ALM LED on, and the COMM LED flashes at a regular frequency. Moreover, I am unable to reconnect CX-Programmer to the processor. I am seeking assistance on resetting the processor to its original state. Any guidance on how to achieve this offline would be greatly appreciated. Thank you for your help! - John
Perhaps a silly question, but have you installed the end cover yet?
Liam Moran asked if the end cover was fitted, which is actually a crucial question. I learned about the importance of the end cover just 15 minutes ago, so thank you for bringing it up. I haven't checked the original equipment yet as the customer provided what they ordered, which seems to be missing the end cover. I also had to buy a power supply myself and will invoice for reimbursement later. It seems like the replacement PLC may also be missing the end cover, just like the power supply was missing. The end cover plays a key role in completing an electrical feedback signal on the expansion bus. Operating the PLC without all the necessary I/O modules mentioned in the project may be causing issues. I may need to address this onsite. Fortunately, I managed to restore communication with the PLC in the CX-ONE environment by adjusting the DIP switches. However, I am now facing an error code 0x00C0, indicating a bus problem, most likely due to the missing end cover. Appreciate your help and insight.
After some detective work, I may have pinpointed the solution to a common issue with PLCs: the importance of the "end cover" component. Without it, you may encounter the frustrating ALM/ERR LED and 0x00C0 I/O bus error message. My NOS PLC was missing this crucial piece, so I ordered one online and inspected its contents. Upon closer inspection, I noticed a small PCB with trace running from pin contacts A1 to A5, alongside a surface mount capacitor. Without the exact match, I decided to take a calculated risk and inserted a 68Ω leaded resistor into the connection. To my relief, this tweak successfully eliminated the ALM/ERR error and illuminated the RUN LED upon program activation. Sharing this experience in the hopes of aiding others in a similar predicament. Thank you, John.
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Answer: - To troubleshoot this issue, you can try resetting the processor to its original state offline. This can help resolve any communication errors and allow you to reconnect the programming software.
Answer: - The ERR/ALM LED staying on with the COMM LED flashing at a regular frequency could indicate communication errors or issues with the program transfer process. Checking the communication settings and ensuring the correct protocol is established can help resolve this.
Answer: - You can try resetting the processor to its original state offline. This may involve performing a factory reset or restoring default settings to clear any errors and allow for successful program transfer.
Answer: - If you are unable to reconnect CX-Programmer to the processor after encountering errors, you may need to troubleshoot the communication settings, check the connection between the computer and processor, and ensure the correct protocol is selected for successful reconnection.
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