HI,

I have a mill with a Fanuc 0M controller. The drive hardware is siemens...

I have the 401 servo alarm (VRDY off) that is thread is about...

It all started one day after the machine was off for about 2-3 months. I had to turn it off, and back on about 8 times to get pass this 401 Error.

What is it does is upon power on, I hear one relay.. the screen shows some software numbers, and then jumps to the XYZ 00000 screen like it always had before, but now, it sits there about 5 seconds like it wants to work, but I hear another relay trip and up comes the 401 servo alarm.

I have looked at the parameters, but I really do not know what they are suppose to be. I purchased the machine 5 times ownership old, and no books or parameter papers came with the machine. Also, it seems that the siemens controller is not popular with people.

I have changed the motors around, and it does not help. They are all 3 the same according to the tags on them. I have pulled the controller board, and this appears ok..

There are some LED lights that come on.

First on bootup, a green LED pops on, and then back off. When the machine CRT displays the XYZ 00000 screen, all LEDs are out, and then that relay trips and a red one on the SIMODRIVE 6RB21 board lights up ( V5 ) at what appears to be the Y axis set of lights. Then the green one, and a red one comes on at V4 and V1

So, somehow I think it is the limit switches, but they are all free and I hear relays clicking. I can put some wedges in the switches like the machine is home, and the error does not come on, but neither does the machine. the boot up hangs at the software version screen and will not continue to XYZ 00000 screen. Pull the wedges, and it will continue to boot, but then 5 seconds or less, the 401 Servo Alarm....

Any ideas?

thanks