1. Introduction to Handshaking Communication with SSC-32
Computer Integrated Manufacturing
© 2016 Project Lead The Way, Inc.

2. Table of Contents Definition Signal Compatibility Components
Optical Isolator
Resistors
Breadboards
Communications:
Lynxmotion to Lynxmotion
Lynxmotion to VEX®
VEX® to Lynxmotion
VEX® to VEX®

3. Handshaking
Handshaking is the process of communication that occurs between a robot and another piece of equipment in a work cell.

4. Handshaking This is a very simple form of communication
A signal is sent from one machine to the robot or from the robot to a machine
Can also be between two robots or two machines
This signal is a simple “on” or “off” – in digital terms, a 1 (on) or a 0 (off). Did you ever notice that the symbol for an on/off switch is a “1” inside of a “0”? Check the computer you’re sitting at!

5. When Is It Used? When a part feeder is empty
When a part is available for pick up or delivery
When an operation is completed
Communication between devices in a work cell is very important. A robot needs to know when to pick up a part, drop it off, or perform an operation. How many different forms of handshaking could be performed in the cell above?

6. Signal Compatibility
When two machines talk, signals should be isolated to protect the machines from incompatible signals
Optical Isolators and Relays are used to do this
Some devices we use have a 7.2V signal, some have 5V signals, and still others have 3.3V signals. What would happen if you sent a 3.3V signal to a machine looking for a 7.2V signal? Would it see it as an “on”? Even worse, suppose you send a 7.2V signal to a device expecting a 3.3V signal. This could damage the equipment!

7. Components: Optical Isolators
An Optical Isolator sends a signal as a light pulse from an LED (1 & 2) on the input side
The output side of the circuit senses the light and sends an electrical signal (4 & 6)
Optical Isolators use a small IR LED connected to the INPUT side of the circuit. When voltage is applied, the LED shines on an IR sensor on the OUTPUT side. This sends the “on” signal with no voltage. It just completes the circuit.

8. Components: Resistor
A resistor is used to limit the amount of current to another component like the optical isolator
Red = 2
A resistor is a component that resists electrical current. We use it to limit the current going to the optical isolator. +
Red = 2 +
Brown = 0
Gold ± 5%
220 Ω ± 5%
Computer Integrated Manufacturing
© 2016 Project Lead The Way, Inc.

9. Components: Breadboards
A breadboard is used to:
Create a simple circuit without soldering
Keep wires as short as possible
Use as few wires as possible

10. Components: Breadboards
The five holes of each row are electrically connected
On the breadboard shown the five holes in a numbered row are connected internally, but the groups of columns labeled a–e and f–j are not. Components such as a microchip must be placed to straddle the middle gap, or pins will be short-circuited.

11. Components: Breadboards
The holes of each column of the bus bars are electrically connected
The pairs of columns on both sides of the breadboard are connected vertically and are called bus bars. These are not used for handshaking.

12. Communication Between Devices
This circuit will be used to handshake between machines
Output
Device
Input Device
Computer Integrated Manufacturing
© 2016 Project Lead The Way, Inc.

13. Basic Circuit for Communications
The five holes of each row are electrically connected
220 Ω
Signal (Yellow or White) 1 2 3 6 5 4 A C B E
(Not Connected)
Ground (Black)
Signal (Yellow or White)
(Not Connected)
Ground Black
4N25 Optoisolator
Computer Integrated Manufacturing
© 2016 Project Lead The Way, Inc.

14. Lynxmotion Robot to Lynxmotion Robot Communication
Example:
When two robots have to perform a task at the same time. or
When one robot needs to wait for another to complete a task.

15. Lynx to Lynx Communication
In the example above, the Lynxmotion robotic arm on the left uses pin A as an input for the switch to start the program from the beginning, although the black wire must always face the outer edge of the SSC-32 board. The same robotic arm uses pin 15 as an output. Any output, 8-15, can be used for this purpose. The black wire, ground, must always connect to the pin closest the outer edge of the SSC-32 board. The Lynxmotion robotic arm on the right waits for this signal on input pin A in the image shown above.
Refer to curriculum to learn how to modify a servo extension to make this connection.

16. Lynx to Lynx Schematic 220Ω Ground Black NC 1 2 3 6 5 4 A C B E
Signal Yellow/White
4N25
Optoisolator
Signal Yellow/White
This is an example wiring diagram. Note what happens internally on the optical isolator. Remember to keep the wires as short as possible, and use as few wires as possible when bread boarding. This will make it much easier to troubleshoot!

17. VEX® Machine to VEX® Machine Communication
Example:
When one machine completes an operation in a sequence, it can let the next machine know when it is safe to begin the next operation.
In this example, a drill press and a grinder made out of VEX components are used.

18. VEX® to VEX® Communication
In the diagram above, the VEX Cortex on the left outputs a signal from Digital I/O 1 configured as a digital output in ROBOTC. The Cortex on the right is using Digital I/O 1 configured as a digital input in ROBOTC. Any of the Digital I/O ports can be used. NEVER USE A MOTOR PORT AS AN OUTPUT FOR COMMUNICATIONS.

19. VEX® to VEX® Schematic
Remember to keep the wires as short as possible, and use as few wires as possible when bread boarding. This will make it much easier to troubleshoot!
Arrows in the diagram above show direction of communication.
When using a VEX component to communicate with another VEX component, the signal to the second component gets inverted due to the optical isolator. Keep this in mind when programming in RobotC.

20. Lynx Robot to VEX® Machine Communication
Example:
When a robot places a part on a conveyor, it can tell the conveyor when it is done.
Machines can be simulated with VEX components and can easily communicate with your Lynxmotion robotic arm.

21. Lynx to VEX® Communication
In the example above, the Lynxmotion robotic arm on the left is using pin 15 as an output in this diagram. Be sure to have the black wire, or ground, always facing the outer edge of the SSC-32 board. Any output 8-15 not already used can be used for this. The VEX Cortex waits for the signal on Digital I/O pin 1. Any Digital I/O 1-12 not already in use can be used. Note that the black wire always goes to the outside edge of the Cortex when using the Digital I/O ports.

22. Lynxmotion to VEX® Schematic
Example
When a robot places a part on a conveyor, it can tell the conveyor when it is done.
The red arrows denote direction of communication. Remember to keep the wires as short as possible, and use as few wires as possible when bread boarding. This will make it much easier to troubleshoot!

23. VEX® Machine to Lynxmotion Robot Communication
Example:
When a machine is performing an operation, it can tell the robot when the operation is complete and it is safe to retrieve the part.
Example: When a machine completes an operation, it can tell the robot that it is finished and that the robot may come and pick up the part. The example above might be a buffer or a grinder.

24. VEX® To Lynxmotion Communication
In this example the VEX Cortex outputs a signal to a Lynxmotion Robotic arm. The Digital I/O 1 port is being used and is configured as a digital output. Digital I/O ports 1-12 can be used for this purpose. The SSC-32 on the Lynxmotion robotic arm waits for this signal on Input pin A.

25. VEX® to Lynxmotion Schematic
Arrows denote the direction of the communication. Remember to keep the wires as short as possible, and use as few wires as possible when bread boarding. This will make it much easier to troubleshoot!
Programming is done in ROBOTC by configuring a digital I/O port as an Output and then using the command SensorValue[]==1 and SensorValue[]==0 to send the signal. See the example in the Teacher Notes.