CNC4PC M28 User manual

M28(Rev. 1.1) User Manual
Revision: 9/11/2009 http://cnc4pc.com/TechDocs/M28R1_1_User_Manual.pdf 1/8
M28- 12OD(24)O EXPANSION BOARD
Rev. 1.1
User manual Rev. 2
1. Overview
This board provides 12 optoisolated sourcing outputs for 24VDC signals.
2. Features
•12 Optoisolated Sourcing 24V
Outputs.
•Darlington Outputs
•24V Common Terminal.
•Screw-On connections for all
terminals. You only have to
screw-on the wires to make all
your connections.
•Fully optoisolated.
•Support for up to 10 KHz
optoisolation.
•Status LEDs on all output
connections. No more guessing.
You can SEE all your signals.
•External Enable Pin (EN). The
board has a pin that allows you to

M28(Rev. 1.1) User Manual
Revision: 9/11/2009 http://cnc4pc.com/TechDocs/M28R1_1_User_Manual.pdf 2/8
enable/disable all the outputs at
once.
•Status outputs LED.
3. Specifications.
DIGITAL OUTPUT SPECIFICATIONS
Maximum output voltage
28V
Typical output current
100mA
Maximum operation frequency
10KHz
Time of transition to high impedance state
12 nS*
*Time passed since a low in the ENABLE input is detected and the outputs are disabled.

M28 (Rev. 1.1) User Manual
Revision: 9/11/2009 http://cnc4pc.com/TechDocs/M28R1_1_User_Manual.pdf 3/8
4. Board description
4.1 Power Requirements
It requires a 24VDC @ 1.5 Amps external power supply to operate.
WARNING
Check the polarity and voltage of the external power source and connect the 24V
.Overvoltage or reverse-polarity power applied to these terminals can cause
damage to the board, and/or the power source.
4.2 Enable pin.
The card must be provided with a 5VDC signal to enable operation. This feature
has been added to enable you to control externally the status of the outputs of the
card. You can add en external switch to provide the enabling signal. Internally this
pin has a 4.7kOhm pull-down resistor.

M28 (Rev. 1.1) User Manual
Revision: 9/11/2009 http://cnc4pc.com/TechDocs/M28R1_1_User_Manual.pdf 4/8
5. Schematics
5.1 Discrete 24V sourcing Outputs
Fig. 1 Outputs schematic

M28 (Rev. 1.1) User Manual
Revision: 9/11/2009 http://cnc4pc.com/TechDocs/M28R1_1_User_Manual.pdf 5/8
6. Wiring Diagrams
Fig. 2 Wiring diagram to connect electromechanical relays.

M28 (Rev. 1.1) User Manual
Revision: 9/11/2009 http://cnc4pc.com/TechDocs/M28R1_1_User_Manual.pdf 6/8
7. Troubleshooting.
SYMPTOM 1: THE BOARD DOES NOT REACT TO THE SIGNAL.
POSSIBLE CAUSE
POSSIBLE SOLUTIONS
- Pin conflict or mach3 configuration.
It is possible that the port address
used for the pin is not right, or that
there is a pin conflict. That is that you
are using that same pin twice. (it could
be assigned to a different function).
- Check that the pin you are using is not
been used anywhere else in your setup.
Got to motor output and output signals,
and check all the entries.
- The board does not like the
waveform it is getting. Changing the
active low status of the pin used also
inverts the waveform.
- Play with the active low status of the pin
used for the frequency.
- The signal or frequencies are not
getting to the board.
- Try a different cable.
- Test the pins in the cable (before they
reach the expansion board) with a
multimeter.
- Problems with Mach3 Pulse
Generation. Mach3 could have
installation problems (you did not
restart immediately after installation),
or there could be something creating a
conflict. Some dongle devices might
cause this, other software, like
QuickTime or drivers for touch screen.
- Test this in a different PC.
- Follow Art’s suggestions for optimizing
up WinXP:
http://www.machsupport.com/downloads/
XP_Optimization.txt.
SYMPTOM 2: THE OUTPUTS DO NOT GET ENABLED / NO SIGNALS ARE
COMING OUT.
POSSIBLE CAUSE
POSSIBLE SOLUTIONS
- The EN terminal (Enable Outputs) is
not enabled. The board requires to be
externally enabled.
- Make sure you are providing +5vdc to
the EN terminal. This +5vdc can be
taken from the terminal next to it.

M28 (Rev. 1.1) User Manual
Revision: 9/11/2009 http://cnc4pc.com/TechDocs/M28R1_1_User_Manual.pdf 7/8
SYMPTOM 3: THERE IS NOISE IN THE SYSTEM.
POSSIBLE CAUSE
POSSIBLE SOLUTIONS
- The board could be underpowered.
- Make sure that main board can supply
+5vdc@300mA to this board.
- There could be a short that could be
draining the power to the board.
- Check that there are no hot spots in the
board or it’s connections.
- Measure the board’s power
consumption, it should be less than
300mA (depending on the features
used).
SYMPTOM 4: AN OUTPUT PIN MIGHT NOT BE WORKING.
POSSIBLE CAUSE
POSSIBLE SOLUTIONS
- A chip may have gone bad. These
buffers could act as fuses for the
signals, and they can go bad because
of noise spikes or even strong static.
- These chips are inexpensive and readily
available. You can order them here:
http://www.cnc4pc.com/Store/osc/index.ph
p?cPath=38_43.
- Carefully moving chips around and
checking if the problem moves around
could be a way of figuring out if this is
the case.
- There could be a problem with the
cable.
- Test this with a different ribbon cable

M28 (Rev. 1.1) User Manual
Revision: 9/11/2009 http://cnc4pc.com/TechDocs/M28R1_1_User_Manual.pdf 8/8
8. Dimensions
All dimensions are dimensions are in Millimeter.
Disclaimer:
Use caution. CNC machines could be dangerous machines. DUNCAN USA, LLC
or Arturo Duncan are not liable for any accidents resulting from the improper use of
these devices. The M28 is not fail-safe device, and it should not be used in life
support systems or in other devices where its failure or possible erratic operation
could cause property damage, bodily injury or loss of life.