Here are the top three causes: You have the MRDLX1 device connected via USB to a computer. The computer sees the SD card as a removable drive (e.g., Drive E:). Even if you are not copying files, the OS polls the drive. The firmware attempts to go exclusive, but the OS holds a shared lock. Result: The firmware refuses to start the print or data acquisition.
Disable USB Mass Storage mode in the MRDLX1 configuration (usually via #define USB_MSD_ENABLE 0 in the firmware config, then reflash). Or physically unplug the USB cable before powering the device. Scenario B: Background File Indexing on the Host PC Windows Search, macOS Spotlight, or Linux updatedb can open the SD card for metadata reading. If the MRDLX1 was previously idle and the PC was connected, the firmware may be unable to elevate to exclusive access upon a new job command. mrdlx1 firmware sd card exclusive
If you have encountered this error message, are designing a custom build, or are troubleshooting a bricked device, understanding this "exclusive" access mode is the difference between a paperweight and a fully operational machine. Here are the top three causes: You have