modicon m340 not responding

I do not know what I did to this plc but I attempted to upload a new program and the plc has seemed to crash, I have error lights as follows, ERR is flashing, CAN ERR is solid red, and CARD ERR is solid red, the plc is a p3420302, I currently cannot access it through USB or Ethernet. I was trying to reprogram using unity pro v.11, I cannot even access it with unity loaded to try to reload the firmware, is there a reset? or reconfigure to get it to recognize the usb?

you can try with Schneider Unity SD cardwriter. You will find it from installation DVD from extras-folder.

Important thing is that you WILL NOT format M340 memory card if windows ask it. If you format card, card is useless after that.

Save *.stu file to memory card with SD writer tool and put card back to CPU (push reset button on power module. CPU reads program from memory card when booting.)


If you have spare CPU, then you can also try uploading firmware files with Unity loader to memory card. Put memory card to spare CPU. Select from unity loader firmaware update, select save to memory card. After unity loader have transferred files to memory card, take memory card from spare cpu, put memory card to defective CPU and push reset button on power module. If you are lucky, then new firmware is readed from memory card

(firmware files can only transferred when memory card is on CPU, SD cardwriter can only transfer stu files directly to cpu.)


If CPU still show error, then there is maybe not much to do and you need new CPU.

Do you know of any way to restore to factory default settings?