Drivers: Will translate the signals to what the stepper motors
will understand, and amplify the translated signals to turn the motors. As you can
see, there are loads of information silk screened on to the case for easy wiring.
That funny looking striped metal piece is for heat dissipation, since these driver
chips can get hot. Specifically, these drivers will be able to accept 24 to 40 volts
with current up to 3 amps. Think of amps as the muscle and volts as how fast the
muscle can be brought into the motors. These also enable microstepping at half,
quarter, fifth, eight, tenth, 1/25, 1/32, 1/50, 1/64, 1/100, 1/128, 1/200 and 1/256
(whew, that was tiring). It even has protection circuitry within for overheating,
over voltage and over current. there are dip switches for easy current switching
and this driver will accept 4, 6 or 8 lead motors. Oh yeah, the most important thing,
thiese puppies have idle current reduction.
Stepper Motors: Provide the linear motion. When the driver sends
a combination of current to the coils of the motors, it will turn 1.8 degrees, or
tighter depending on the microstep setting on the drivers. That is, if you have
half step, then the shaft will turn .9 degrees per step, quarter step .45 degrees
per step, and so on and so on... These are NEMA 24 motors (standards terminology
which only refers to its faceplate specifications and measurements), but don't let
the size fool you, these motors can hold at 382 oz-in or 425 oz-in of torque (depending
on availability). The current rating is 2.8 amps and 4.17 volts, so you will need
a power supply that can be drawn at 8.4 amps, which is a nice segway to the power
Shaft sizes for the NEMA 24 are 1/4" and NEMA 34 are 1/2", typically.
Wiring diagram: Wiring diagram for
3-axis using the standard breakout board
If the motors are not turning, and you are wondering why? Below is a few simple
steps you can take to localize the issue. These steps assume that you have Mach3
or another control software installed and the interface requires a parallel cable.
1. To determine if there is a signal coming out of your computer, you will need
to probe the port on the back of the computer and jog to see if the voltage changes.
You will need a multimeter. Test each pin that you set as output. If no signal,
it is a software or computer problem.
2. If there is a signal at the port, plug in the parallel cable and test the other
end to see if the cable is showing output. if not, the cable is bad.
3. If there is a signal from the parallel port, probe the respective pins on the
breakout board, if not, then the breakout board may not be configured properly (jumpers).
4. If there is a signal, you are half way there. Then we will need to check the
Here is a great guide that was developed by one of my customers, David W, as he
was troubleshooting his own electronics:
Trouble shooting - Build your CNC - diagnostic - motors won't /don't work
This is one trouble-shooting guide to the Blacktoe CNC table based on my experience.
It begins at the point when you have followed all of the instructional materials
to build the table, installed Mach3 on a desktop PC, configured the motors, plugged
in the parallel cable, tried to jog one of the axises... and gotten nothing. It
is also assumes that you have a multimeter and the basic tools. Here are some additional
resources that you will probably want to read before you get started:
Mach 3 documentation: http://www.machsupport.com/documentation.php
Here we go:
1. Before we start properly, if you haven't already, disengage the transmissions
by taking the chains off the sprockets to avoid an un-expected movement that might
damage you or your machine. Also, be sure you don't electrocute yourself either
-- unplug the logic system when you are working in the wiring (and be careful when
you are testing). Disconnect your parallel cable for now (as long as you are at
it, make sure you have the right cable -- you need a Straight Thru Serial DB25M/DB25M
like this one [ http://www.amazon.com/Belkin-25ft-Straight-Serial-DB25M/dp/B00004Z5W7
]). Also, restart your machine just to make sure you are starting fresh.
2. Download, install and start up a parallel port monitor:
This will give you immediate feedback on which pins are conducting at hi and lo
voltages. Remember: "In TTL circuits, any voltage between 0 and 0.8 volts is called
"lo" and any voltage between 2.4 and 5 volts is called "hi"."
3. Double-check your "Ports and Pins" configuration.
In Config/Ports and Pins/Motor Output you want these values:
X, Y and Z set to Enabled
X, Y and Z set to Step Low Active
X-axis: Step Pin #: 2
X-axis: Dir Pin #: 3
Y-axis: Step Pin #: 4
Y-axis: Dir Pin #: 5
Z-axis: Step Pin #: 6
Z-axis: Dir Pin #: 7
4. Go into Config/Ports and Pins/Input Signals/EStop and click on "Active Low".
Mach 3 cannot disable the EStop, so this will "reverse" the emergency stop to inactive
on a lo signal (such as when the plug is disconnected). You will click this setting
on and off several times during trouble-shooting as you connect and disconnect the
port cable, so get to know it:
Active Lo for when the cable is disconnected
Active Hi for when the cable is connected
5. In the Program Run screen, jog the X-axis a few times back and forth while looking
at the parallel monitor. You should be able to jog the X and Y axis by hitting the
arrow keys on your keyboard, but if you hit the Tab button, you can bring up a jogging
sub-screen that will let you jog it with the mouse. Note the location and colors
of the pins on the top right corner of the array (pins 1 through 7) and how they
change when you change direction. Note that pins 3, 5 and 7 will change from Lo
to Hi when you alternate directions.
Red = Hi Signal (2.4 - 5.0 Volts)
Green = Lo Signal (0.0 - 0.8 Volts)
6. Confirm these values by testing the parallel port connection in back of your
PC. You will need to look closely to find the pin numbers on your port because they
are printed very small, but they should be back there. Insert the black probe into
the #1 Pin (should be Lo) and probe each successive pin (2-7) with the red probe.
Do the voltages correspond to the values being reported by the parallel port monitor?
In my case, the Lo signal was 0.0 - 0.1 Volts and the hi signal was 3.3 Volts. Change
directions a few times to confirm. If not, your problem lies before the parallel
port output from your PC.
7. Now connect the parallel port cable to the back of your PC *but not your breakout
board yet*. Re-test the voltages at the end of the cable the same way you tested
them in back of the PC. It will be a bit trickier this time because you have to
contact the pins instead of letting the probe be held in the holes, but it's manageable.
Are you getting the appropriate voltage readings? If not, you might have a bad/wrong
8. Now you can plug the parallel cable into the breakout board again and plug in
the breakout board and driver power supplies -- there should be LED lights lit up
on every component. You will notice that Mach 3 will go into EStop mode because
you now have a hi signal going to the PC, so go back into Config/Ports and Pins/Input
Signals/EStop and toggle off "Active Low". Hit the reset button and try jogging
the X-axis a few times. If nothing happens, move onto the next step.
9. Check the power-supply wiring to the breakout board. Is the light on? If not
you might have your circuit reversed. Is there a loop running from the 5V power
supply to the "EN" pin on the board? If not your board is not engaged. Test it by
placing the red probe on the 5V pin and black probe on the #2-7 output pins. If
your board is engaged properly, the Hi signal output should be about 5.5 Volts (note
the increase in voltage). If it is not engaged, it will be running about 1.5 Volts
on each pin.
While this is by no means a comprehensive trouble-shooting guide, it should help
you isolate any issues you might be having in your system and hopefully get you
started a little sooner.