Thread: +5V TTL Signal

  1. #1
    Hi Guys
    I`m trying to use the Spindle commands M3 (ON) and M5 (OFF) in Mach3 to generate the TTL Signals to
    open/close my micro-dispensing valve. Mach3 is set to use Port 1 Pin 16 and this connects to the s c r e w terminal
    of my Xylotex 4 Axis Board.

    Now my problem. Without the valve connected in any way I can issue a spindle ON command and measure 3.90 volts
    between pin16 and GND on the s c r e w terminal, as soon as I connect this to my valve driver the voltage drops to 1.7v
    I`m getting no signs of life on the valve.
    How come I`m not measuring 5v with nothing else connected ?
    and why is the voltage dropping to 1.7v

    Would it be possible to use a 2nd port in Mach3 and maybe send the spindle signal out on the RS232 (COM1 Port)
    then at least it would be independant of the Xylotex Board.

  2. #2
    John S's Avatar
    Lives in Nottingham, England, United Kingdom. Last Activity: 3 Hours Ago Has been a member for 9-10 years. Has a total post count of 1,950. Received thanks 127 times, giving thanks to others 44 times. Referred 1 members to the community.
    Probably because your valve driver is needing too much current ?
    What about taking pin 16 and putting it thru a small relay and then using a separate 5v volt supply to trigger the valve driver.
    You only have 3.9 volts to start with so you probably only have a 3.5 volt mother board and not a 5 volt MB.

    John S.
    John S -

  3. #3
    Hi John
    Thanks for your reply.
    That sounds like a good plan. So if I`m reading it right, Pin 16 gets the signal from Mach3 - tells the relay to release the 5v. When pin 16 drops the signal the 5v returns to zero ?

    Please bear in mind I`m a complete dunce with electronics, I`ll need to be shown how to build the relay circuit.
    any help would be very appreciated.

    I want a dedicated PC for this project and have cobbled together an oldish system
    AMD Athlon XP 1800+
    1.53 GHz
    640 RAM

    On the Xylotex there is 5v available on the small connector where I have stuck the Limit Switches Common wires. It`s marked VCC is there anyway I could tap into that ? ?

    EDIT :: 3 mins later
    I have just turned on the system and physically touched the TTL signal wire for the valve onto the VCC 5v on the xylotex
    and yep the valve looks like it`s working.

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