Centroid Community CNC Support Forum

The motherboard on the computer that run my lathe died, so I changed the computer. now when I power up the MPU11-GP104D (not the Computer or cnc11) the axis both move erratically till they hit a hard stop. didn't touch the mpu11 or the GP104D. what can cause that?

You need to include the normally-open contacts of the GPIO4D fault relay (the relay next to OUT16) as part of your emergency stop contactor coil loop, as well as using one of the 16 PLC-programmable relay outputs as a "No Fault" output.

My guess is that you changed CNC11 versions from 3.04 or earlier, to some version between 3.06 and 3.10. In those versions, from power-on until the CNC11 software starts talking to the GPIO4D, the GPIO4D axis enables may be on (low) and the analog output may be -10V (full scale reverse).

If you combine that condition with an improperly-wired emergency stop loop (one that fails to include the GPIO4D fault relay), then you can get a runaway on powerup.

If I recall correctly, there was some dependency also on the drive fault status: the signals wired to INP17-INP20. If you did not see this condition before, and you have not changed CNC11 software versions, then perhaps something changed in whether your drives are holding the fault inputs open or closed on power-up.

You should ensure that your emergency stop contactor coil loop is wired as recommended. You should also update to CNC11 v3.12 or newer.

it was a bug in the CNC 3.06. it stopped when I updated to 3.16

Does your Emergency Stop contactor coil loop pass through a "NoFaultOut" PLC output relay, and also through the internal Fault relay on the GPIO4D?

If it does not, you should correct it so that it does.