i am converting an older Anilam Eagle cnc km-750..
during the course i have gotten most everything working once again with a new drive package..
i am using  LeadShine M860 stepper driver in 1600 microstepping mode and Leadshine  4.5 NM NEMA34 motors ( 1/2" shafts) in parallel coil configuration and a cnc4pc c-10 breakout board ( one more on order  for i/o)  the axis tests are perfect ( almost better than original.. .0002 resolution) ..  someone had the brains to have a ball screw cover..

the problem..
the spindle once had a vfd and had an air controlled variable spindle speed setup...
i am converting the air system  with a stepper .. and the vfd is toast..  i have spent so much money in fancy controls and doo dads..  i am holding off on a replacement vfd for a few months.

 i am replacing it with a set of 3phase contactors.. one for cw the other for ccw  and one for e-stop that kills power to the whole motor circuit. ( for redundant protection)

the problem i am wondering is  when i issue a m3 or m4  command  is there an xor designed into the software to prevent the simultaneous  output on both the pins assigned to m3 and m4?

or should i design a safety circuit that xor's the output and ands them back into the relays controlling the 3phase contactors?

another question is the output of the signal of the m3/4  is it a pulse or is it a sustained signal high or low until i issue a m0  or e-stop.

way too many questions .. but i have not seen the topics  asked or answered yet..









 

The M3 and M4 will toggle one or the other and when assigned different outputs will not both be on at the same time.
The output signal from the M3 / M4 command is a steady state high or low.

I never leave anything to chance with 3 phase so, if it is possible, it would not hurt to incorporate an interlock into your contactors just to be sure to be sure 

Tweakie.

thanks..  i thought it would be that case.. but wanted to be sure.. i will still build the xor safety circuit  just to be certain that it is not possible to  cross phases during a crash or catastrophic software failure..
 

The software should only activate one or the other but personally I would not rely totally on software. Depending on your contactor type you may be able to get a mechanical link between them which will prevent one being operated if the other is already operated, my lathes contactors were like that.
Regards output, it is a steady signal and also M5 will also stop it.
Hood

ah too slow in typing I see

exactly..


 i want to idiot proof the design.. JIK someone else decides to bypass the contactor interlocks..  ( stranger things have happened) ..
 how is Scotland tonight?

Afraid I dont know how Scotland is tonight as its only morning

Safety is always a good thing, especially when talking mains voltages.

Hood