Images Scientific OWI Robotic Arm Interface Kit (PC serial) Article
Images Company Robotic Arm PC Interface allows real time computer control and an interactive
script writer/player for programming and playing robotic arm motion. Re-playing script files
demonstrates basic automation and animatronics. The serial interface connects an IBM personal
computer or compatible to OWI’s Robotic Arm Trainer (TM) through the computers serial port. A
computer’s USB port may be used with a USB to Serial Adapter.
WIN 98/XP Program
Install the Windows program by inserting the CD-ROM into the computer’s CD drive. Click on the
Start Button on Windows toolbar, then click on the Run option. A dialog box opens, choose the
Browse option and highlight the setup.exe program on the CD-ROM. The set up program creates
an Images Directory on your hard drive, installs all the necessary files and places an icon on your
start menu task bar.
The robot arm may be operated interactively, by clicking on the various function buttons on the
screen. See page 3 for screen image. Writing script files is also interactive, this allows the user to
focus on the robotic arm performance rather than writing a file. Script file writing is explained in
greater detail, under Creating Script Files.
Construction
Start kit construction by identifying the component side of the printed circuit board (PCB). The
component side has the white line drawings of the resistors, transistors, diodes, IC's and DB9
connector. All components are mounted on the component side. In general after soldering a
component to the board, clip away any excess wire from the underside of the printed circuit
board. Follow the sequence for mounting the components as outlined. Start by mounting and
soldering the 100K resistors (color bands brown, black, yellow, gold or silver) labeled R1 through
R10.
Next mount the 3.3K, 1K, 4.7K, 10K, and 300 ohm resistor (R11). For the color bands of the
preceding resistors see resistor color code appendix. Mount the red LED labeled D1 on the
board. The positive lead of the LED is the longer lead. The positive lead of the LED is mounted in
the + label . Next mount the 18 pin socket for U1. Mount and solder the DB-9 right angle
connector, labeled P-1. Mount the On-Off (SW1) switch and the LM2940 (Q11) +5 V voltage
regulator. Mount and solder the five TIP120 transistors (Q1 to Q5) and the five TIP125 transistors
(Q6 to Q10). Mount and solder C1 (100 uF) and C2 (10 uF) capacitors, keeping the positive
terminal of the capacitor orientated as shown in the drawing above. Next mount and solder the 4
Mhz crystal and two 22 pF capacitors. Finish the project by mounting and soldering the 8 position
3 inch Molex connection cable starting with the red wire being placed in the first hole next to onoff switch, Q12 (2N3904 transistor) and the 5.1 V Zener diode, orientate the diode as shown in
the drawing above. Mount the preprogram 16F84 chip into the 18 pin socket.
Solder the Molex connector to the PC board as shown in the above and side pictures. The wires
are different colors to make it easier to keep the wires aligned when soldering.
Connecting the Interface to Robotic Arm
Connect the interface to the base of the robotic arm using the 8 position cable, making sure the
Molex connect is properly seated in the base platform of the robotic arm, see figure below. The
interface draws power from the robotic arm power supply when it is turned on. A 6 foot DB-9
cable is included in the robotic arm kit. Use this cable to connect the computer's serial port to the
robotic arm interface.
Using the Robotic Arm Interface:
Initially the power to the interface should be turned off. Start the Serial Interface program, then
turn on the interface.
Clicking on any function button will initiate the robotic arm to perform that function. Clicking on the
same function button a second time will stop that function. In addition instead of clicking on the
same function button a second time to stop a function you may also click on a second function
button, this will stop the first function from performing as before, and initiate the robotic arm to
perform the second function immediately.
Robotic Arm Doesn’t Move:
If you click on a function button the robotic arm doesn’t move at all you probably have the
program set to the wrong COM port. Select another COM port. If a particular COM is not
selectable (ghosted) the program has determined that your computer does not have that COM
port available.
Writing Script Files:
To write script files, click on the button labeled “Interactive”. The button name changes to
“Program”. This lets you know you are in the “programming” or script writing mode. Any function
clicked on now will be written into a script file. When you click on a function, the robotic arm
performs the function like in the interactive mode, but in addition information on the function is
written into the the yellow script file box on the right hand side of the screen. The function name is
written and it is given a step number. When the function button is click for the second time it stops
the function, the time elapse between button clicks is entered into the third column. Instead of
clicking the same function button a second time a user may also click onto a new function. This
will stop the first function, write the time elapse into the 3rd column as before and immediate write
and start performing the new function. A user may program up to 99 functions, including timed
pauses, into a single script file.
To stop writing a script file click on the button labeled “Program”. The button name changes back
to “Interactive”, letting you know you are back in the interactive mode. Script files may be save
and loaded to the local directory.
Playing Script Files:
Script files may be automatically re-played up to 99 times. Enter a replay number in the “Repeat”
number box then click on the “Run Script” button.
For anyone wishing to write their own program to communicate to the serial interface to control
the robotic arm here are the communication Protocols
2400,n,8,1
Numbered Output
Robotic Arm Response
0
Pause
3
Base CCW
4
Base CW
5
Shoulder Up
6
Shoulder Down
7
Elbow Up
8
Elbow Down
9
Wrist CCW
10
Wrist CW
11
Gripper Open
5
Gripper Close
Parts List:
Printed Circuit Board (PCB)
DB-9 Cable
DB-9 Female Rt. angle connector (P-1)
(5) Tip 120 Transistors
(5) TIP 125 Transistors
2N3904 Transistor (Q12)
LED (red) (D1)
(10) 100K resistors
330 ohm 1/4 watt resistor (R11) (or 300 ohm)
3.3K ohm 1/4 watt resistor
10K ohm 1/4 watt resistor
4.7K ohm 1/4 watt resistor
1K ohm 1/4 watt resistor
100 uF capacitor (C1)
10 uF capacitor) (C2)
(2) 22 pF capacitors
4 Mhz crystal
16F84 PIC Microcontroller (pre-programmed)
Toggle switch
6” 8 conductor cable with Molex connector
LM2940 +5 Voltage Regulator (Q11)
18 pin socket
Determining Resistor Values
Resistor values are read using the color bands on the body of the resistor. The first band is the
one nearest the end of the resistor. Start reading from this band. The first band represents the
first significant number, the second band, the second significant number and the third band is the
multiplier. If the third band is gold or silver this indicates a multiplier value of .1 or .01 respectively.
Color
Black
Brown
Red
Orange
Yellow
Green
Blue
Violet
Gray
White
Value
0
1
2
3
4
5
6
7
8
9
Multiplier
1
10
100
1000
10000
100000
1000000
10000000
100000000
1000000000
Tolerance (%)
Gold 5%
Silver 10%
No Band 20%
Example: A resistor with the color bands of Red, Red, Orange, Silver
1st Number Red = 2
2nd number Red = 2
3rd Number Orange = 3 multiplier (number of zeros) that equals 1000
Silver = 10%
Putting it all together:
Red
2
Red
Orange
2
x 1000
Value
= 22,000 ohms
Tolerance
+/- 10%