I attached 840D alarm list, from your statement --you have a running machine. if no one made any HW or SW ,parameter change. you need check your C44 axis control card and power section (someone call it drive). you can easily find the faulty drive --it will have red led on the front of control card. I suggest 1st step check encoder cable and motor cable connecting,  then check control card number , if you have same card in the machine of another axis, sweep to try. that will be simple, after change card you will know . next step is check or replace power section (drive, possible 15A or 25A and so on) , the last step is check motor itself  

please feedback

MS_PL

Hello!!

I have a problem with a control Sinumerik 840D (ShopTurn 6.4) & Simodrive 611 in a lathe CTX210; the alarms appears are: 300501 (axis c44 drive 1 supervision of maximum current), 25201 (c44 axle drive fault).

The problem occurred while the machine was running, now the errors are immediately after power on.

I am asking for tips on where to look for the fault.

Best regards,

MS_PL