spindle motor on while booting the pc!

problem of the LPT port is the undefined state and behavior during the boot of the computer. If I switch on your CNC lathe usually the stepper motor driver is immediately activated. During the boot sequence of the controlling computers, some LPT pins are toggled or are in an undefined state. This might result in Undesired spindle motor on thus undesired motion of the CNC lathe. In order to prevent this behavior, In present situation I cut off the power (230V isolation switch off, it will cut off power to all the power to cabinet.24V psu,external power for cooling fan,230V for contactor coil etc.bob only powerd by computer) to motor contactor to avoid switch on while booting the computer after that power on the switch for contactor.

Is it good for bob?
Other solutions for avoid this problem?

That is normal.
To avoid that, do not power the machine until the PC has booted and switch off the machine before turning off the PC.

Using a charge pump is one way to prevent undesired affects during boot up. I have a machine that has a charge pump input on the stepper drivers but I am missing the documentation for the drivers so I am not using the charge pump. I turn on the PC first then the power to the machine as you do.

More info on charge pump is here. wiki.linuxcnc.org/cgi-bin/wiki.pl?About_Charge_Pumps

a hal-enabled power relay is also enough so it also serves as an emergency.

billykid wrote: a hal-enabled power relay is also enough so it also serves as an emergency.

That does not work for parallel port as it is used to send diagnostic data during boot.
Charge pump is a very nice solution fro that, one can be made using RC filter and a darlington transistor and a relay.

mea culpa .. I haven't used the parallel for a long time