Today, I'm going to share a story about an incident that occurred while I was debugging at the company. It concerns the S7-1500 CPU memory card.
We all know that the SIMATIC S7-1500 series PLC's CPU itself does not come equipped with memory (Load Memory). It requires a SIMATIC memory card to be inserted in order to operate. One day, the electrician informed me that the wiring for the new equipment had been completed and it was ready for debugging. So, I checked the connections and powered it up. Before long, I encountered an issue: the CPU was always in STOP mode. What was going on?
The convenience of the S7-1500 lies in its CPU having a display panel, allowing for direct diagnostic access to check for error reasons. So, I entered the Diagnostic interface, and I found that in the "Used Memory" section, the "Load Memory" displayed "nan%", as shown in the figure below:
This seems to indicate a rhythm of not finding the memory card. Clicking on [OK] to enter the submenu, I discovered that both "Available Memory", "Used Memory", and "Free Memory" were all showing "0 Byte", as depicted in the figure below:
Clearly, the current issue lies with the memory card. Opening the display panel, I observed that there was a card inserted into the SD card slot. Could it be that the memory card wasn't inserted properly? Removing the card for inspection, I identified the problem. It wasn't a SIMATIC memory card but rather a SIMATIC HMI card, as illustrated in the figure below:
So I found the CPU memory card again. Look, this is what it looks like:
When inserting the card, it should be oriented in this direction:
The properly installed SIMATIC memory card can be seen in the "Memory Card" section under "PLC Overview," as shown in the following figure:
Alright, this is a little story that happened during my debugging process. I hope you enjoy it. Also, I hope that if you encounter similar issues during your debugging process, you find it inspiring.