MX3660 Input Sourcing Help


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Thread: MX3660 Input Sourcing Help

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    Default MX3660 Input Sourcing Help

    Hi-

    Can someone explain to me how input sourcing works inside the Leadshine MX3660?

    More specifically, why does this schematic in the manual have 2 ground connections? One is from the auxiliary 12 volt power for proximity switch and the other is to the ground of an unused input channel.

    Is the additional power supply required because the unit cannot supply enough amperage to run specific switches? Why not ground everything to the same input?

    Figure 18 of this manual (http://www.leadshineusa.com/UploadFi...660hm_V1.2.pdf)

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    Default Re: MX3660 Input Sourcing Help

    It looks like the fig 18 in the MX3660 manual is wrong !

    see page 19 in PDF manual V1.2
    MX3660 Input Sourcing Help-mx3660hm_v1-2-pdf


    part of diagram from MX3660 manual

    MX3660 Input Sourcing Help-mx3660-inputs-jpg


    in the MX4660 manual , this shows the internal opto-isolator circuit

    MX3660 Input Sourcing Help-mx4660-input-opto-isolators-jpg


    this is what I think the MX3660 input wiring should be

    MX3660 Input Sourcing Help-revised-mx3660-proximity-sensor-input-wiring-jpg


    this is what I would expect the missing MX3660 internal opto-isolator input circuit to be

    MX3660 Input Sourcing Help-mx3660-input-opto-isolators-jpg


    if you assume the internal +12V supply is connected , via a 1K resistor , to the anode of opto-isolator's LED

    the input pin will source a current of about 10mA when the input pin is connected to the ground pin
    (about 2V will be dropped across the LED , I = 10V / 1000 ohms = 10 mA )

    the open circuit voltage between the input pin and the ground pin will be approximately 12V depending on the current taken by your volt meter





    John

    Last edited by john-100; 12-06-2017 at 08:26 AM. Reason: add ref to 1K opto-isolator's LED current limiting resistor


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    Default Re: MX3660 Input Sourcing Help

    Fantastic! This makes way more sense now. Thank you.

    For my knowledge can someone explain the function of the capacitor, resistor and diode in parallel on the internal side? Is it to expedite the turn on speed on the octocoupler?

    http://tinyurl.com/y7p8sg9a

    I've modeled the circuit here and guessed at some values. Feel free to tweak it to make it behave correctly.

    Last edited by CountryGib; 12-06-2017 at 08:52 AM.


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    Default Re: MX3660 Input Sourcing Help

    LED's are not very good rectifiers as the reverse breakdown voltage is about 5 or 6 V and can easily be damaged

    if the input pin is connected to +12V from your proximity switch for instance, while the power to the MX3600 is off
    the diode will conduct instead of the LED breaking down

    the capacitor across the LED is an alternative position for a noise filter capacitor
    instead of using a capacitor between the input pin and ground

    the resistor in parallel with the LED & capacitor provides a discharge path

    the resistor must be chosen so it does not divert too much current from the 1K resistor supplying the LED current
    but not take too long to discharge the capacitor when the limit switch opens


    MX3660 Input Sourcing Help-mx3660-input-opto-isolators-diode-rc-network


    I think your thinking of the speed up capacitor in this circuit

    MX3660 Input Sourcing Help-speed-capacitor-jpg

    John



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    Default Re: MX3660 Input Sourcing Help

    Got it.

    For my application I have a Z touch plate (that allows current to flow when tool touches plate) and touch probe (that activates inverse | current cut when activated).

    With my setup both need to be connected to the same input pin for my controller software to recognize activation.

    I'm trying to avoid constantly flipping the input from active high to low when changing tools.

    Is it possible to make a circuit that would allow current to flow when a switch is open and not flow when the switch is closed?

    This seems possible with an external power source, but is it possible using the source feed of one input of the MX3660?

    MJ



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    Default Re: MX3660 Input Sourcing Help

    is this the kind of thing your looking for ?

    MX3660 Input Sourcing Help-n-o-touch-plate-n-c-probe

    the N/C probe grounds the input of the inverter its connected to and switches off the open collector output

    the 1K pull up resistor connected to the open circuit touch probe
    switches on the first of a pair of inverters

    the second inverter is wire ORed with the inverter connected to the N/C probe
    the OR junction is pulled high by a 1K resistor and is buffered by another pair of inverters

    the open collector out put that connects to the MX3660 input is switched off

    when either the N/C probe opens or the touch probe is grounded
    the MX3660 input is grounded so it will be set up as active LOW
    and the LED indicator will be switched on


    the circuit uses a 74HC06 open collector inverter

    MX3660 Input Sourcing Help-7406-hex-open-collector-inverter-jpg




    John

    PS

    a 12V version could be made using a CMOS open drain inverter like MC14069

    the resistors will need to be 2.5 to 3 times higher

    Last edited by john-100; 12-06-2017 at 04:44 PM. Reason: add descripton of how the circuit works and ref to 12V version


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    Default Re: MX3660 Input Sourcing Help

    I think i understand.

    All of the inverters required would stem from one 74HC06 chip correct?

    Would 74HC04 suffice? It has 6 outputs. I'm having trouble finding 74HC06.

    https://www.mouser.com/ProductDetail...SABEgKSzPD_BwE

    Does this model look correct to you?
    http://tinyurl.com/y8sh7fhb

    Last edited by CountryGib; 12-06-2017 at 09:49 PM.


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    Default Re: MX3660 Input Sourcing Help

    mouser have the 74LS06 which will work

    John



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