M241 PLC Led Err blin, no usb or ethernet

[MistrzZen]

I have an M241 PLC with a blinking error LED. According to this document, I attempted to update it using an SD card, but the PLC didn’t read anything—only a single blink of the SD card LED occurred.

After a thorough inspection, including measuring on-board voltages and checking with a thermal camera, everything seemed fine. The current consumption of the main IC was around 300mA on a 1V power supply, which appeared normal.

As a next step, I reballed the main IC (Spear 680-2). After this, I was able to update the PLC via the SD card, but the device still wasn’t detected via USB (despite the driver being installed) or Ethernet, even when connected through a router.

I also reballed the DRAM and Micron memory IC, but this had no effect. My final attempt was to update the BIOS chip directly. After that, the Spear IC became visible via USB, but the PLC didn’t function correctly, as expected.

Has anyone encountered a similar issue and found a solution?

[asisnaira]

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@MistrzZen wrote:

I have an M241 PLC with a blinking error LED. According to this document, I attempted to update it using an SD card, but the PLC didn’t read anything—only a single blink of the SD card LED occurred.

After a thorough inspection, including measuring on-board voltages and checking with a thermal camera, everything seemed fine. The current consumption of the main IC was around 300mA on a 1V power supply, which appeared normal.

As a next step, I reballed the main IC (Spear 680-2). After this, I was able to update the PLC via the SD card, but the device still wasn’t detected via USB (despite the driver being installed) or Ethernet, even when connected through a router.

I also reballed the DRAM and Micron memory IC, but this had no effect. My final attempt was to update the BIOS chip directly. After that, the Spear IC became visible via USB, but the PLC didn’t function correctly, as expected.

Has anyone encountered a similar issue and found a solution?

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You’ve already taken several good steps, but the issue might still be with the main Spear IC or related components. Since reballing the ICs allowed the device to update but not fully work, it suggests potential deeper hardware issues with the Spear chip or memory

[MistrzZen]

From my point of view the spear is good becouse when i dump bios ic with firmware from sd card i think then bios firmware isnt comaptible and spear goes into boot mode so my first thought is corrupted bios, is it possible to recive it from support? Second thought is NAND chip if SLC is used that means about 100k of cycles so some bad sectors can be possible.

[lowedirect]

Hey! That sounds like a serious deep dive — props to you for going that far with reballing and BIOS flashing.

I’ve had a somewhat similar issue with an M241 where it wouldn’t respond over USB or Ethernet after a failed firmware update. In my case, the SD card update didn’t work until I reformatted the card to FAT32 and used a smaller capacity (4GB). Might be worth double-checking that too if you haven’t already.

Since your Spear IC is now visible via USB post-BIOS flash, it does sound like you’re on the right track. Maybe there’s still an issue with the firmware layer not fully initializing the comms stack? I’d try a firmware reflash using EcoStruxure Control Expert via USB if the device shows up—even if it’s just partially.

Let us know how it goes! Would love to hear if you manage to get it fully back online.