1. Communications Electronics for Ag. Machines ISOBUS
Lecture 8 ISO Part 6 / Virtual Terminal
BAE 5030 – 503
Summer 2011
Instructor: Marvin Stone
Biosystems and Agricultural Engineering
Oklahoma State University
May 26, 2011
BAE

2. Virtual Terminal (VT) Concept
Serves as a “human interface” between operators and “implements” on an ISO bus
VT provides both output (display) and input (buttons and controls) functionality to the operator
A Working Set, a CF or Group of CFs, composes the logical entity that represents the implement that the operator interacts with
VT provides a standardized means for displaying information and receiving operator input from a Working Set
VT appears as exclusively available to a particular implement but multiple implements may use terminal simultaneously
An Implement using the terminal is not necessarily aware of other Implements using the VT.
Operator may switch the active panel and key inputs from one Implement to another.
May 26, 2011
BAE

3. Virtual Terminal (VT) Example
Planter and Sprayer Simultaneously use Terminal
Operator can switch to see either planter or sprayer
planter or sprayer each have complete use of the terminal and may be unaware of each other
Many other implements may also be connected, eg. tractor, GPS guidance system, task controller
May 26, 2011
BAE

4. Example Virtual Terminals
A method on the terminal may be used to switch implements
Implement 1
Implement 2
Implement 3
Implement 1
Data Mask
Kvernland Tellus VT
Soft Key
Mask
Implement 2
Implement 3
May 26, 2011
BAE

5. Working Set Definition
Working Set consists of a group of CFs created by one manufacturer and designed to work together as a single entity
After Power-ON and successful Address claims each Working Set Master sends a stream of messages to the VT identifying:
Master and number of members
Each member of the working set
The VT allows a Working Set Master and its members as a set to connect and use the terminal
May 26, 2011
BAE

6. Network Model for VT Communications
Working sets consist of at least one master and may have slave CAs
The VT communicates with the WS master. WS Master and slaves download Object Pool elements and interact with the VT.
VT replies are sent to the WS Master (except configuration 4 and later are sent to the originator)
Implement 2
Navigation / GPS
May 26, 2011
BAE

7. Connection management
The VT when it is functional on the bus sends the VT Status message on change of status and once per second.
Working Sets use this message to determine that the VT is operational and not busy.
Loss of this message for longer than 3 seconds indicates to the WS that the VT has been turned OFF or is disabled.
The Working Set Maintenance message is sent by the WS to the VT once per second when the working set has initialized
VTs use this message to determine when the WS is operational
Loss of this message for longer than 3 seconds indicates to the VT that the WS has been turned OFF, removed or disabled. If this is an unexpected shutdown, the WS’s object pool is deleted.
May 26, 2011
BAE

8. Typical VT initialization message traffic
May 26, 2011
BAE

9. VT operator interface components
Data Mask Display
Navigation
Method
200 x 200
Min
+ +
- -
Mono
16 or 256
Color
Edit
Method
ESC
Soft Key Mask Display
Auxiliary
Assignment
Method
Soft
Keys
Control
Method
May 26, 2011
BAE

10. Soft Keys
Soft Key Mask created by Working Set is used to define displayable information and Key Code
One set of Keys (a Mask) may be selected at a time by the Working Set
VT provides for methods of scrolling keys if virtual softkeys are provided
VT informs WS of available keys in Metrics response
Working Set controls menu hierarchy
Soft Key Mask Display
Text Go
Stop
Operator key selection method (Hard Keys) A B C D E F
May 26, 2011
BAE

11. VT operator interface component examples
Case IH AFS Pro700
Navigation
Touch Screen
Soft Keys
Touch Screen
Control Method
Parker ISOBUS VT
Navigation
DICKEYjohn X30
May 26, 2011
BAE

12. VT Interface Components
Auxiliary Input (Optional)
May be built into VT or remote
Working sets may contain Auxiliary Inputs and/or Auxiliary Functions
Messages included to allow VT to: assign Auxiliary Inputs to Auxiliary Functions
Auxiliary Input Types include
Boolean ON/OFF and ON/OFF/ON
Latched
Non-Latching
Etc.
Analog
Return to 0%, 50%,
Quadrature
Bi-directional encoder
Touch screen / Mouse Support
Button Object
Auxiliary Input 1
Auxiliary Input 2
May 26, 2011
BAE

13. Auxiliary functions
Auxiliary functions allow operator to control specific functions independent of the VT screen interface
Auxiliary inputs (keys, switches, dials, knobs, sliders), provided by one or more working sets (or the VT), are active at all times after being assigned to an auxiliary function
Auxiliary inputs are assigned to auxiliary functions (i.e. raise/lower, start/stop, set position) and are also provided by one or more working sets (or the VT).
The operator assigns the inputs to the functions using a proprietary auxiliary assignment screen provided by the VT
May 26, 2011
BAE

14. Auxiliary Function Example
Implement (working set) provides a “raise/lower implement” auxiliary function
An auxiliary input, a two position momentary toggle switch, located on the armrest of the tractor (associated with the tractor ECU working set) of a type that is compatible with the auxiliary function is available
The operator, using a screen provided by the VT, assigns this switch to the “raise/lower implement” function.
The function of the switch does not change unless changed by the operator
May 26, 2011
BAE

15. Auxiliary Function Assignment
Working Set masks contain Auxiliary Input objects
Working Set masks contain Auxiliary Function objects
A protocol is provided to allow WS to announce status of both auxiliary inputs and auxiliary functions
VT provides a proprietary screen with auxiliary object designators (provided in the WS object pools) to allow operators to assign auxiliary inputs to functions
VT uses any stored previous assignments
VT notifies Working Set of assignment of Input Functions to Objects
Working Set acknowledges
Operator may re-assign Input Functions
WTK Elektronik
Multi-Functional-Handle
May 26, 2011
BAE

16. VT Alarm Interface Components
Alarm Mask Object
Defines screen
Priority
Assignable by Working Set
When mask is selected by CF
VT overlays entire Data Mask Area
Active alarm masks are ordered highest priority first, then first alarm first
Soft Keys can be used when the alarm is active
Some acknowledgement method used to clear the alarm
Acoustic Alarm Signal Object may be included
Selectable duration, frequency, repetition, volume
May 26, 2011
BAE

17. VT Language management
Language Message
VT (virtual terminal) sends this message after the system has completed its power-on and address claims
A default language is stored in the Tractor ECU and retrieved by the VT in case the desired language is not supported by the implement ECUs.
The VT shall provide a method for the operator to view the supported language list of a connected implement or implement pool and to select a language from this list.
Contains language code, number format, decimal symbol, date format, units for common parameter types, and units system
May 26, 2011
BAE

18. Destination specific group function message
VT protocol Messages
Destination specific group function message
VT identifies sender via Source Address
ECU identifies VT via Source Address
May 26, 2011
BAE

19. Communication of Object Pools to a VT
Pool is Encapsulated in Transport Protocol
One or more sessions may be used but only one type of TP
Message sent to begin the pool is the:
Object pool transfer message with a data field that contains VT Objects
The message sent to finalize transmission of the pool is the:
End of Object Pool message
The VT responds with the:
End of Object Pool response message
Pool is a Collection of Objects in the data field of the Object Pool Transfer message
Object Object ID Type Attributes and Data …
Object Object ID Type Attributes and Data …
Object Object ID Type Attributes and Data … …
And so on
May 26, 2011
BAE

20. VT Object Transport Protocol
Used for pool transfer and for any 9 byte or longer messages
Uses both standard Transport Protocol and Extended Transport Protocol
Multi-packet message protocols
Standard: Up to 1785 bytes message data
Extended: 1786 to 117,440,512 bytes message data
Connection management
Sender: Requests to Send
Receiver: Clear to Send n-Packets
Sender: Sends cleared packets …
Receiver: Acknowledges completion
Missed packets may be requested by receiver
May 26, 2011
BAE

21. Extended Transport Protocol
Uses existing Connection Mode Transport Protocol with additional extended functions (BAM may not be used)
Can transport up to 117,440,512 bytes (117 M bytes)
Uses a sequence number offset to increase the range of packet sequence numbers
Actual extended message sequence number = (ETP.DT Sequence number + ETP.CM_DPO Data Packet Offset)
The ETP.CM_DPO Data Packet Offset is sent after every Clear to Send (ETP.CM_CTS) message to provide the extended sequence number
Four new control functions are defined to distinguish the Extended Transport Protocol from the normal Transport Protocol
Control Byte 20 Extended message Request To Send (ETP.CM_RTS)
Control Byte 21 Extended message Clear To Send (ETP.CM_CTS)
Control Byte 22 Extended message Data Packet Offset (ETP.CM_DPO)
Control Byte 23 Extended message End of Message Acknowledgment (ETP.CM_EOMA)
Standard connection abort message is retained
May 26, 2011
BAE

22. Message sequence for the Extended Transport Protocol
May 26, 2011
BAE

23. Screen Description
A mask defines screen and contains objects that describe screen elements
A mask can define data screens, softkeys or alarms
May 26, 2011
BAE

24. Example screen objects
Output String
Line
Boolean input
Numeric Input
List Input
Picture
Graphic
Numeric Output
Input Button
May 26, 2011
BAE

25. Input and Output Fields
VT Display Objects
Input and Output Fields
String
Numeric
List input
Shapes
line
rectangle
ellipse
polygon
Picture Graphic (Bitmap)
Seeding Rate
20,000
Choice #1
Choice #2
Choice #3
May 26, 2011
BAE

26. Complex Graphic Objects
Meter Object
Bar Graph Object
Arched Bar Graph
May 26, 2011
BAE

27. WS updating a numeric display on a VT
Numeric value on the display can be updated with two CAN packets
The VT responds and indicates if any error occurred
May 26, 2011
BAE

28. Changes in object attributes
May be through commands from the WS or through event triggered macros
May 26, 2011
BAE

29. Events signaled from the VT to the WS
VT Events including soft key press, button press, input object select, pointing events, escape, change numeric value, change Mask, change soft key mask, change string, hide/show user layout, and audio signal termination signal the WS through a message.
May 26, 2011
BAE

30. Storage Management in a VT
Commands
Get Versions
List of all version labels for Working Set.
Store Version (by Label)
Stores volatile resources of Working Set.
Load Version (by Label)
Delete Version (by Label)
May 26, 2011
BAE