1. Use of Multiple Devices
FESA: Introduction
Use of Multiple Devices 1
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2. Defining Multiple Devices
FESA: Introduction
Data fields defined in the device-data section
Properties defined in the device-interface section
Devices are defined in the instance file
The Eclipse Plugin provides editing tools to work with device definitions:
Table Editing View: 2
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3. Working with Multiple Devices
FESA: Introduction
The number of devices in a deploy unit is only known at run-time
Get/Set Actions – the device in question is available as a parameter
Realtime actions
The device collection contains all devices that can trigger the action
The device collection can be filtered (see selection criteria later)
Your code may select which devices (e.g. isMockDevice)
void GenerateNumber::execute(fesa::RTEvent* pEvt) {
std::vector<Device*>::iterator device;
for(device=deviceCol_.begin();device!=deviceCol_.end();++device)
If ( (*device)→isMockDevice.get()
// fake reading
(*device)→number.set(42,pEvt→getMultiplexingContext()); }
Else
// real reading
(*device)→number.set(driver->read(),pEvt→getMultiplexingContext()); 3
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4. Device and Global Data
FESA: Introduction
Global Data items are the same for all devices in a FESA class
global-data
acquisition and setting data
global-interface
Acquisition and setting properties
There is always only one global device
The Global Device has no events-mapping so unique actions cannot be triggered
Actions triggered for a device may access the global device
By default a class includes the global Diagnostic property used for logging and tracing 4
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5. Use of Global Data
FESA: Introduction
The Global Device is intended for use by the class developer or expert
The Global Device is present in the database
There is no standardised nomenclature for applications to easily access the global device
Design the the global-interface for FESA Explorer use
For tasks such as device aggregation or collection of statistics it is recommended to use a class association
Use the global device to share state between devices
The Global Device and hence data can be accessed in code via the Service Locator 5
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6. Working with the Global Device
FESA: Introduction
Example: Ambient temperature compensation
Read a temperature sensor at longer intervals and store as global data
When individual devices are measured retrieve ambient from the global device and perform compensation
void ReadSensor::execute(fesa::RTEvent* pEvt) {
double ambientTemp = this->MyClassServiceLocator_->getGlobalDevice()
->ambientTemperature.get(pEvt->getMultiplexingContext());
std::vector<Device*>::iterator device;
for(device=deviceCol_.begin();device!=deviceCol_.end();++device)
double value = driver→read(device->hardwareID);
value = compensationFunction(value,ambientTemp);
(*device)→sensorValue.set(value); } 6
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7. Exercise: Global Data Build on a class with a timer event
Create a global acquisition data item, e.g. ambientTemperature
Configure the timer event to trigger an RT-Action for one device
In the RT-Action set the global data via the Global Device
Create a Server Acquisition Property
Add a value-item, do not link it to any data fields
Create a custom Get Action
Copy data from the Global device to the data container
(Code Snippets: Usage of client-data in server-actions)
Add extra devices in the instance file
From FESA Explorer communicate with each device

8. Selection-criterion
The device-collection includes all devices that may process an event by default
To limit the device-colection for a specific event use the selection-criterion

9. Selection-criterion
The selection-criterion allows you to execute a RTAction for a set of devices that fulfill the same filter criteria.
This device-selection must be created at design time.
Each device-selection will run in a separate instance of the RTAction.
The selection-criterion can be based on:
hardware-fields: host and logical-address.
device's name, description, accelerator, timingDomain and mainMuxCriterion.
fields.

10. Concepts selection-criterion One or more operands
Select for equal field-values
All equal operands have the same RTAction instance
selection-rule
Define the logical connection between the different operands
Unary-operation (directly define relevant operand)
Binary-operation (define result of an operation between two operands)

11. Field-value Refer to any field Two possibilities:
Implicit: FESA will create one device-group for all devices which share the same field-value.
Explicit: The user has to specify a value. All devices with that value will be in the same device-group.

12. Binary/Unary-operation

13. Example
You have 5 devices in your .instance file with a numeric field called groupNumber. The groupNumber will be:
For the Device1Group1 the value will be 1.
For the Device1Group2 and Device2Group2 will be 2.
For the Device1Group3 and Device2Group3 will be 3.
Also you have 3 RTA triggered by the same event.
You can check it in your .design file.
Run the deploy unit in order to see how all the RTA iterate all the devices.
Exercise:
The RTA1 , the deviceCollection should contain only devices with groupNumber=1
The RTA2 , the deviceCollection should contain only devices with groupNumber=2
The RTA3 , the deviceCollection should contain only devices with groupNumber=3
On any problems: