J Tech Photonics Pic-Convert Manuel utilisateur
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J Tech Photonics, Inc. Pic-Convert™ Board Instructions V2.7 Copyright 6/13/17
Pic-Convert™ Board Instructions
This is the fifth version of the Pic-Convert board and now has fully isolated inputs and provides a power
supply to make the solution completely industrial. This DAC+PWM board solution has been developed
with Jeff and John at picengrave.com for use with their picengrave software for laser image
engraving. This board uses the STEP and DIRECTION signals from a spare axis to output a PWM signal (or
analog) to a laser driver for laser power control. This allows software controlled CNC machines (like
Mach3) to adjust the laser power on the fly for image engraving applications.
With the board you will now adjust your laser power by MOVING the axis you selected to hook up.
There is also an enable signal to turn the laser on and off.
Features
•Convert Step and Direction signals into PWM or analog output for laser drivers.
•PWM output for PWM modulated drivers.
•Analog output for analog modulated drivers.
•Output Enable Relay to control output with M03/M05 command.
•Fully isolated inputs allow for more industrial applications.
Contents of the box
In the box for the Pic-Convert™ there should be the circuit board with enclosure and 7 volt 1 amp wall
power supply for connecting power.
Safety
This board is designed to work in conjunction with high power lasers. When using lasers always make
sure you take the appropriate precautions for safety including the use of protective eyewear and
shielding. Always use caution when operating CNC equipment.
Using the board
There are two ways in which to use the Pic-Convert™ board:
1. Connecting it to a laser driver that uses PWM to modulate the laser intensity.
2. Connecting it to a laser driver that uses ANALOG to modulate the laser intensity.
Set-Up Video
https://youtu.be/Jqj29GKFXdo
Input Specifications
The Pic-Convert™ board requires DC voltage signals for step, direction, and enable pins. We recommend
using 5 volt signals. The inputs are all opto-isolated and can handle up to 24 volts.
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J Tech Photonics, Inc. Pic-Convert™ Board Instructions V2.7 Copyright 6/13/17
Power Specifications
The Pic-Convert™ comes with a provided 7V power adapter. If you want to use a different power
supply, the board requires a voltage higher than +6V. You can use a power supply that is larger (up to
24volts), but make sure the regulator does not get too hot. A 9V or 12V supply should be easy to find.
Connection Overview
INPUTS (left side of the board):
Direction + : Direction encoder signal for the axis chosen in control software.
Direction - : Connect to the GND signal for your Breakout board or controller.
Step + : Step encoder signal for the axis chosen in control software.
STEP - : Connect to the GND signal for your Breakout board or controller.
Output Enable + : This will enable the output of PWM or Analog on the OUT header.
Output Enable - : Connect to the GND signal for your Breakout board or controller.
OUTPUTS (right side of the board):
OUT: Output for the PWM (or analog) signal.
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J Tech Photonics, Inc. Pic-Convert™ Board Instructions V2.7 Copyright 6/13/17
Power Overview
The board requires >+6v. We have provided a 7V wall style power adapter with the board. We
recommend using this adapter as it provides a clean isolated power source.
You can also use a power supply that is larger (up to 24volts), but make sure the regulator does not get
too hot. The regulator is the IC right next to the barrel power connector. If needed for higher voltage
operation, a heatsink can be added via the screw hole on the package.
There are three ways to power the Pic-Convert™ board:
1. Barrel type connector power supply. Either use the enclosed plug to wire connector provided
2. Screw Terminals connections.
3. Solder points for wire connection.
Jumper Settings
The jumpers come pre-set at the factory for PWM and Relay Enabled.
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J Tech Photonics, Inc. Pic-Convert™ Board Instructions V2.7 Copyright 6/13/17
J2: To enable PWM output, set to PWM (top two) on both J2.
To enable ANALOG output, set to Analog (bottom two) on both J2.
J4: To enable relay control input signals, jumper on left two (Relay Enable).
To override the output relay, jumper on right two (OVERRIDE).
Theory of Operation:
This board takes the step and direction output of an axis on your controller and turns it into a PWM duty
cycle (or analog) based on the position of the axis. You can choose any extra axis your controller has, or
you can use the Z axis. If you use the Z axis, just remember to either disable your motors or take off the
motor connections before you run it.
Now your laser can be controlled ON and OFF with the ENABLE input on the Pic-Convert™ board. You
can use the spindle enable command in mach 3 for this.
Then, control the power with the axis commands. “Movement” on the axis will create a signal to the
laser to control the power level. You will learn how to set up what movements will create what power
levels in the next few sections of the manual.
You can see in the next few pictures what the signal to the laser will look like at different power levels.
50% Power.
PWM (Yellow)
Analog (Blue)
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J Tech Photonics, Inc. Pic-Convert™ Board Instructions V2.7 Copyright 6/13/17
100% Power.
1% Power.
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J Tech Photonics, Inc. Pic-Convert™ Board Instructions V2.7 Copyright 6/13/17
Linearity
The Pic-Convert™ board provides a duty cycle or analog voltage output based on an increment from the
step and direction output on your controller. It is imperative that this output is linear for the 256 shades
of greyscale will show exactly on your image. Here is the output for both versus increment. It is 99.99%
linear in both applications.
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J Tech Photonics, Inc. Pic-Convert™ Board Instructions V2.7 Copyright 6/13/17
Set Up for PWM Output (J Tech Photonics Driver Example)
In order to use the Pic-Convert™ board for a PWM output you will need to get the step and direction
signals for the axis you are using. You can either get them from your breakout board or you can use a
dual breakout board to get the signals. You can get a dual breakout board from our store if you need to
find one.
Once you have these signals, connect them to the appropriate input screw terminals on the Pic-
Convert™ board. You can also use another output to control the relay to enable the output of the board
with the M03/M05 command. This adds an extra safety precaution that the laser will not be enabled
without the appropriate command from the controller. Connect this to the "OUT ENABLE" screw
terminal.
Make sure the jumpers on J2 are set correctly for PWM operation. THE BOARD WILL START AT 50%
OUTPUT UPON APPLYING POWER TO THE BOARD. YOU NEED TO SEND A COMMAND TO SET IT TO
ZERO WHEN IT TURNS ON. We recommend jogging the axis until you see no light coming out of the
laser. It will now be ready to start engraving your file.
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J Tech Photonics, Inc. Pic-Convert™ Board Instructions V2.7 Copyright 6/13/17
Setup for Analog Output with Power Enable Control
This setup is similar to the PWM connections. You will still need the Step and Direction signals for your
axis of choice. You will connect them the same as in the previous example.
Set the Jumper J2 to ANALOG (lower on J2). If you want relay power control then choose it on J3.
Connect the controller output M03/M05 signal to the "Driver Enable" input if you want to control the
pass through power.
Connect the modulation input of the laser driver to the output screw terminal on the Pic-Convert™
board.
THE BOARD WILL START AT 50% OUTPUT UPON APPLYING POWER TO THE BOARD. YOU NEED TO
SEND A COMMAND TO SET IT TO ZERO WHEN IT TURNS ON. We recommend jogging the axis until you
see no light coming out of the laser. It will now be ready to start engraving your file.
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J Tech Photonics, Inc. Pic-Convert™ Board Instructions V2.7 Copyright 6/13/17
General Software Settings
Like in the theory section, we saw that the board has different levels for each position on the axis.
Depending on how you have your steps per inch (or mm) set will determine the distance you will need
to achieve your proper engraving.
In this example we have it set on the Z axis:
You will need to set your machine to get the perfect settings. The board is 8 bits, so there will be 256
steps in this range. Your feedrate will determine the “darkness”level at the maximum steps. Faster =
lighter and slower = darker.
To get the "perfect" results for your material, you can first find the minimum value for just starting to
burn the material. This level will be your minimum value for PicLaser SW. Your max level will be 256
steps from 0. If your steps are 10000 per inch, then your increment will be 0.0001" and your maximum
level is -0.0255. Here is what it looks like conceptually:
So, if your wood starts to burn at -0.002", then your minimum value will be -0.002" and your maximum
value will be 256 increments more at -0.0255". This will give you the full "grey scale" levels you need.
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J Tech Photonics, Inc. Pic-Convert™ Board Instructions V2.7 Copyright 6/13/17
Mach3 Setup
Here are some standard settings in Mach3 that Jeff at picengrave.com suggests from his experience with
the Pic-Convert™ board. Units are in INCHES.
Steps per inch: 10000
Velocity: Calculated by your machine controller
Accel: 30
Step Pulse: 5
Direction Pulse: 5
This makes your incremental move distance = 0.0001"
Jeff recommends using the “A” axis because it has keyboard jogging enabled and a digital readout on the
mach3 default screen
This example is for the C axis, but it can be also "A", "B", or "Z" as well:
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