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  1. #281
    Chaz It is in the manual about page 37 and it clearly shows how they are connected. so the data is going via the cat5 cable so you are not limited by the 5 inputs on a PP
    Last edited by Clive S; 08-06-2017 at 12:14 PM.
    ..Clive
    The more you know, The better you know, How little you know

  2. #282
    Quote Originally Posted by Chaz View Post
    Ok, fundamental question.

    Is it normal or acceptable to use the same switch (mechanical or proxy) for both home and limit? I dont understand how the machine would know if it was simply sent home or it actually needs to stop as its a limit. Is there logic that says 'ref all' and it goes home but if its hits the home limit during any other movement (manual or programmed) that the machine will then stop?
    Chaz I think you are getting bogged down with all this. When you home the machine the software knows that you are homing and therefore treats the switches as (homes) when the machine has homed the software then treats the switches as limits.

    In your case you will have plenty on inputs so why not keep them separate. (it is also OK to use just one switch for home and one end limit)
    Last edited by Clive S; 08-06-2017 at 12:14 PM.
    ..Clive
    The more you know, The better you know, How little you know

  3. #283
    I agree with Clive in his post above (Hi Clive !)

    However my personal preference on big powerful machines is to have the home switches inside the boundries set by the limit switches, and have the limit switches trigger powering off of the drives. Also to have the limit switches within the boundries of mechanical stops that limit travel before ball screws over travel.

    With a big servo driven machine like my CNC Beaver Partsmaster Mill, or the Traub lathe I rebuilt last year (now sold), the servo drives are a few killowatts, so if they run away damage WILL be done without limits.

    However that said, my CNC Plasma Table is set up sharing home and limit switches driven by Mach3 - it's how the chap who originally built it made it, and it wasn't easily altered when I re-built it. But the drives are steppers and only Nema 46's so in the worst case if it runs away not much breaks !

  4. #284
    Chaz's Avatar
    Lives in Ickenham, West London, United Kingdom. Last Activity: 2 Hours Ago Has been a member for 4-5 years. Has a total post count of 963. Received thanks 67 times, giving thanks to others 42 times.
    Quote Originally Posted by Clive S View Post
    Chaz I think you are getting bogged down with all this. When you home the machine the software knows that you are homing and therefore treats the switches as (homes) when the machine has homed the software then treats the switches as limits.

    In your case you will have plenty on inputs so why not keep them separate. (it is also OK to use just one switch for home and one end limit)
    Thanks. The penny dropped, just never knew this before.

  5. #285
    Neale's Avatar
    Lives in Plymouth, United Kingdom. Last Activity: 2 Hours Ago Has been a member for 4-5 years. Has a total post count of 968. Received thanks 164 times, giving thanks to others 5 times.
    Clive has just answered the home/limit question - Mach3 knows what you are doing so treats the switch inputs accordingly. There is a minor gotcha with this. If you use a switch with effectively no offset between on and off positions, you can get problems (to be more accurate, I had problems) with this. Z homed, then X and Y started moving. The Z switch had swapped from homing to limit function, and the slight vibration caused the Z switch to trip and stop the machine ("limit switch event"). Fortunately, the IP/M has the capability to move the axis very slightly away from the home position immediately after homing which fixed the problem.

    The limit on number of inputs only applies if you are using a parallel port. That statement on the Mach3 config page is a bit misleading. There are only five input pins on a parallel port as all the others are output only, so the limit is a physical one and nothing to do with Mach3. You will be fine with the IP/A and are free to use all the ports. I doubled up my switches (combined upper and lower) mainly to reduce the number of wires needed and I still have some unused inputs on the IP/M.

    Don't worry about voltages. Desertboy was talking about Arduinos and they are definitely 5V only. The IP/A will be very happy with 24V signalling, and in fact this gives much better noise rejection. The CSMIO kit is built to use the industry standard 24V signalling. No pull-up/pull-down resistors needed, but watch the wiring instuctions carefully so that you get it right. Less flexible motion controllers only have one input pin but there are two per channel on the IP/A. There are plenty of examples of how to wire NPN n/c proximity switches in series if you do a Google search - I have had four in series working reliably in testing although in practice I only wire them in pairs on my machine.

  6. #286
    Chaz's Avatar
    Lives in Ickenham, West London, United Kingdom. Last Activity: 2 Hours Ago Has been a member for 4-5 years. Has a total post count of 963. Received thanks 67 times, giving thanks to others 42 times.
    Quote Originally Posted by Neale View Post
    Clive has just answered the home/limit question - Mach3 knows what you are doing so treats the switch inputs accordingly. There is a minor gotcha with this. If you use a switch with effectively no offset between on and off positions, you can get problems (to be more accurate, I had problems) with this. Z homed, then X and Y started moving. The Z switch had swapped from homing to limit function, and the slight vibration caused the Z switch to trip and stop the machine ("limit switch event"). Fortunately, the IP/M has the capability to move the axis very slightly away from the home position immediately after homing which fixed the problem.

    The limit on number of inputs only applies if you are using a parallel port. That statement on the Mach3 config page is a bit misleading. There are only five input pins on a parallel port as all the others are output only, so the limit is a physical one and nothing to do with Mach3. You will be fine with the IP/A and are free to use all the ports. I doubled up my switches (combined upper and lower) mainly to reduce the number of wires needed and I still have some unused inputs on the IP/M.

    Don't worry about voltages. Desertboy was talking about Arduinos and they are definitely 5V only. The IP/A will be very happy with 24V signalling, and in fact this gives much better noise rejection. The CSMIO kit is built to use the industry standard 24V signalling. No pull-up/pull-down resistors needed, but watch the wiring instuctions carefully so that you get it right. Less flexible motion controllers only have one input pin but there are two per channel on the IP/A. There are plenty of examples of how to wire NPN n/c proximity switches in series if you do a Google search - I have had four in series working reliably in testing although in practice I only wire them in pairs on my machine.
    Awesome, thanks.

    Suppose now I need to decide if its proxy and mech or only proxy. I could do mech as primary home / limit and proxy as limits via E Stop circuit.

  7. #287
    Chaz's Avatar
    Lives in Ickenham, West London, United Kingdom. Last Activity: 2 Hours Ago Has been a member for 4-5 years. Has a total post count of 963. Received thanks 67 times, giving thanks to others 42 times.
    My drive will likely support limits too although Id have to undo some of the wiring already done to accommodate this.

  8. #288
    On my IP/A setup i used mechanical limits and mechanical homes, two limits and one home per axis.

    My limits are a high power circuit (24v contactor circuit as opposed to a logic circuit) as they are wired to a PILZ relay for the safety circuit which cuts all power to the drives if tripped - I really did not want to risk runaway blowing the end brackets off my table :)

    The homes are inboard of the limits and i use home-offset to set the locations.

    It all works well here.

    When using mechanical switches, get quality ones with Gold-flashed contacts, these will not degrade under logic levels, normal switches rely on an arc to keep the contacts clean - these will fail pretty fast at logic voltages.

  9. #289
    Chaz's Avatar
    Lives in Ickenham, West London, United Kingdom. Last Activity: 2 Hours Ago Has been a member for 4-5 years. Has a total post count of 963. Received thanks 67 times, giving thanks to others 42 times.
    Quote Originally Posted by Davek0974 View Post
    On my IP/A setup i used mechanical limits and mechanical homes, two limits and one home per axis.

    My limits are a high power circuit (24v contactor circuit as opposed to a logic circuit) as they are wired to a PILZ relay for the safety circuit which cuts all power to the drives if tripped - I really did not want to risk runaway blowing the end brackets off my table :)

    The homes are inboard of the limits and i use home-offset to set the locations.

    It all works well here.

    When using mechanical switches, get quality ones with Gold-flashed contacts, these will not degrade under logic levels, normal switches rely on an arc to keep the contacts clean - these will fail pretty fast at logic voltages.
    How do I know if they have gold flashed contacts? Quick look at RS doesnt seem to show that level of detail and their details are normally fairly generous.

  10. #290
    When using mechanical switches, get quality ones with Gold-flashed contacts, these will not degrade under logic levels, normal switches rely on an arc to keep the contacts clean - these will fail pretty fast at logic voltages.
    In my opinion standard switches will be fine. (remember logic levels are 5V) the op is using 24 V.
    ..Clive
    The more you know, The better you know, How little you know

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