Home to switches

[PaulIngram]

Hi

I have a Lathe retrofit. Allin1dc with CNC11. When it is started, the controller wants to home to marks. I want it to home to + Limits

I have checked the cnct.hom file, all looks well with M92 and M26 for both X and Z axis.

There is a parameter to suppress homing on startup, that is set to default 0.

If I MDI the commands that are in the cnct.hom file, they all work fine. It looks like somewhere I have managed to set the system to not call cnct.hom.

Can anybody advise how / where I can change this back to home to switches automatically ?

Thanks

Paul

[cncsnw]

1) On the Control Configuration screen, set "Machine home at pwrup" to "Home Switch"

2) On the Machine Configuration -> Motor Parameters screen, set the numbers in the "Home +" column to the PLC input numbers where you have your home switches wired. These may be the same inputs/switches as your plus limits, or they may be different if you prefer to have separate switches.

If you do use a separate home switch, you need to make sure that the home switch remains tripped (open) all the way out to where the limit switch opens. Otherwise, if you have the axis sitting beyond the home switch (between the home switch and the limit switch), you will be unable to automatically home.

[PaulIngram]

CNCSW

Thanks very much.

As you suggested, it was the Control Configuration Screen setting. I knew I had seen it somewhere, just couldn't recall where.

Best Regards

Paul

[cncsnw]

For the record, as long as you have non-zero home switch numbers entered in the columns of the Machine Configuration -> Motor Parameters screen, then it does not really matter whether you have selected "Home Switch" or "Ref Mark-HS" on the Control Configuration screen. You just need to make sure you have not selected "Jog" there.

The difference between "Home Switch" and "Ref Mark-HS" only comes into play when the required home switch input number is set to zero.

With "Home Switch" homing, and zero for the input number, M91 or M92 will look for a hard stop: it will drive the axis until it sees a rise in position error and motor load, which it will interpret as a hard stop at the end of travel. It will then back off to an encoder index pulse. You can adjust the load threshold by parameter. In current CNC11 software it is Parameter 187. This method is prone to false homing if your machine has, or develops, tight spots in its travel.

With "Ref Mark-HS" homing, and zero for the input number, M91 or M92 will move only as far as the next encoder index pulse. Before homing, the operator must jog the axis so it is inside one turn of the motor, on the correct side of the desired home position.

With "Ref Mark-HS" homing, and a non-zero input number, M91 or M92 will home to the specified minus or plus home switch, just like in "Home Switch" homing. This in spite of the prompt message on the screen which tells the operator to jog to the reference mark.