Regarding the reset (formatting) of the S7-300
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The last edit to this post was made by LZ Gas Station on 2015-12-24 at 15:16. There is an MMC (memory card) from another device; I wanted to format it before using it. According to the methods described online: set the mode switch to MRES and hold it there until the STOP light stays on for about nine seconds, then quickly switch it back to STOP within two seconds, and immediately reset it to MRES again. At this point, the STOP light will flash rapidly, indicating that formatting is in progress. Keep the switch in the MRES position until the STOP light stays on, indicating that the formatting is complete. ”But my procedure seems to differ slightly from the description; I never saw the “STOP light flash rapidly”. Then, multiple operations were performed in “Diagnosis/Settings – Clear/Reset”, after which the desired items were downloaded. However, during the upload process or when comparing blocks, it was found that the blocks in the program were not cleared; in my project only OB1 was used, but after uploading, blocks such as OB35, OB80, FC1, FC2, etc. appeared, which are clearly data from the original project. So I think the formatting of the MMC card might not have been done properly. How to solve it, find a solution! ! !
The MMC card cannot be formatted in MRES format under normal use conditions. If you want to clear the program, you can do so in the following way: 1. Use the “View > Online” menu command in STEP7 to open Blocks online, select the block that needs to be deleted, and use the “Delete” key to remove that program block from the card. This is similar to a RAM card. 2. Use “PLC >Download User Program to Memory Card” to download an empty program. 3. Use the Siemens programmer PG or a Siemens-specific card reader to delete or perform formatting.