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Messages - MN300

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General Mach Discussion / Re: Looking for good DIY controller kit supplier
« on: November 19, 2020, 08:29:01 PM »
When I read your earlier post about having 5 motor wires I assumed the last wire was white and brown. If there are really 6 wires then 'color code 1' under '6 lead wires' would seem to apply.

You asked if the A axis channel could be used with the X axis motor. They seem to be identical so if you can setup the software to address it that should work. Remember to transfer the encoder wiring. Note that the diagram shows that unused encoder inputs should be grounded.

As a last resort you could try swapping encoders between axes. This may entail some risk of damage or incorrect installation so I hesitate to suggest it.

General Mach Discussion / Re: Looking for good DIY controller kit supplier
« on: November 19, 2020, 11:40:44 AM »
The circuitry.com file shows a circuit for unipolar stepper motors. 5 wire connection is a common configuration for unipolar motor. Unipolar motors are slower and less powerful than bipolar.

If you need to replace more TIP120s use TIP122. It has a voltage rating of 100V instead of 60V for the TIP120. This will help if your failures are caused by voltage spikes.

TPS's suggestion of swapping motors will help troubleshoot the problem.
One of the motor wires  will read the same resistance to all the other wires. Color codes vary but that common winding center tap is probably the white and brown wire.

General Mach Discussion / Re: Capacitor on Limit Switch
« on: September 29, 2020, 11:25:01 AM »
The delay on switch opening is a few tenths of a millisecond at most. The Spice Simulation shows the switch input (yellow) and the opto current (red).

The point at which the opto output opens depends on the version of the PC817 used. Peak OPTO LED current is about 15 mA. If the turn-off point is 2 mA then the delay is 0.1mS.

Diode D10 is in the simulation to make the V1 voltage pulse generator behave like switch contact. It isolates the voltage pulse generator when low to simulate the open switch contact.

General Mach Discussion / Re: Capacitor on Limit Switch
« on: September 28, 2020, 10:38:06 PM »
Yes, the cap is in the wrong place. It should be across the opto input.

General Mach Discussion / Re: Quad Level Shifter boards - Prox sensor
« on: September 01, 2020, 05:43:33 PM »
Some users may want to add screw terminals to the BSS138 level shifter board.

Disclaimer: I ran across the level shifter  board while researching parts for a non-CNC project and have not used it myself. Pictures on the website show the board with header connectors added and plugged into a standard breadboard which would have 0.1" spacing.

I searched for a terminal strip to match that spacing and found this terminal strip at Digi-Key. Other vendors have similar terminals.

More expensive version from Farnell

 I can't judge the distance from the mounting holes to the resistors so they may or may not fit on the top of the board but should fit on the bottom.

General Mach Discussion / Quad Level Shifter boards - Prox sensor
« on: September 01, 2020, 11:22:15 AM »
There have been several posts about connecting 12V proximity sensors with built in pull-up to break out boards (BOB). Those solutions usually involve adding a couple of discrete components for each input leaving the user with the problem of how to mount them. This device provides the necessary circuitry on a ready made board.

There are a number of sources for a quad level shifter board based on the BSS138 MOSFET. They are made for Arduinos and similar systems but should work well for interfacing  BOB inputs to higher voltage systems.

The low voltage side (LV)  can work with the 5V logic levels common to CNC equipment. The high voltage side (HV)can accept up to 24V. Actually the BSS138 is rated for 50V max but we should allow a wide margin of safety.
This device works with active low logic inputs. The BOB inputs may not be setup with a pull down resistor.

 The BSS138 level shifter is bi-directional. A low level signal on either side is transfered to the other. I am suggesting this device be used for input to a BOB but it could be used in limited cases for output. The problem is that the high side output current may not exceed the BOB's  output current. You would have to research the allowable BOB output current and ensure it's greater than the load by a reasonable margin.

Connect the BOB's 5V and ground to the LV and GND terminals. Terminals LV1 to LV4 connect to your BOB board IO.
Connect the high voltage side power to HV and ground to GND. NOTE: this device does not isolate the grounds like an opto board. Terminals HV1 to HV4 will accept signals from NPN prox switches. It's OK if they have their own pull-up to their power supply voltage. You can also use limit switches to ground as the BSS138 board has its own pull-up resistors. While switches and open collector outputs do work directly connected to the BOB this could be useful where you have a mix of input types and want to protect again accidental connection to a high voltage input.


I currently don't have the means to test this. You need to edit the enable switch input and select a travel speed.

-- X only MPG Code --
SigLib = {
    [mc.ISIG_INPUT10] = function (state)
-- Pendant function.
function RunPendant()
    local hSig, rc = mc.mcSignalGetHandle(inst, mc.ISIG_INPUT10) -- Is mapped to Port ? Pin ? *X Selection
    local XSelection, rc = mc.mcSignalGetState(hSig)

    if XSelection == 1 then
        mc.mcMpgSetAxis(inst, 0, 0) --X Axis
        mc.mcCntlSetLastError(inst, "X Selected")
        mc.mcMpgSetAxis(inst, 0, -1) --No Axis
        mc.mcCntlSetLastError(inst, "No Axis Selected")

        mc.mcMpgSetInc(inst, 0, .001)  -- travel per encoder step

You will need a switch to enable the X axis, otherwise the MPG will always be active.
Load the Lua code provided and strip out the unused selections.
You also don't need the PenJogOn output, it's for an LED. The Pendant Estop input is optional too.

General Mach Discussion / Re: Chinese BOB with 2010 a funny one.
« on: August 13, 2020, 10:18:14 PM »
Set the VFD for 0-10V whilst you are adjusting the attenuation trimpot. Once it's setup for 5V at 100% PWM switch to 0-5V - job done.

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