FairNET Receiver

Operator Menu Location: Generic Hardware Operators Networking FairNET

Operator Bitmap:

 
Functional Description:
The FairNET Receiver generic hardware operator provides access to a networking channel resource in the physical hardware. When the generic operator is linked to a specific networking hardware resource, it will receive messages broadcast over that channel resource using the FairNET protocol.
FairNET Receiver operators decode FairNET messages broadcasted over a network. The operator has three outputs:
•Output is the value of the broadcast signal obtained from the network. It is analog or digital depending on the receiver type (analog or digital).
•Output indicates if the value has changed since the last transmission. For an analog signal, the value change must exceed a user-defined dead-band parameter to be declared as having changed. The output is HIGH during the single schema compute cycle in which the signal value change was detected; otherwise it is LOW.
•Output indicates if the broadcast transmissions are being received regularly (i.e., indicates if the network link is good). It is LOW while transmissions are regularly received, and the output is HIGH if the operator has not received a broadcast in a user-specified time interval (the Broadcast Dead-Time property of the receiver).
Analog broadcast signals are encoded into a 16-bit integer that can assume distinct values (0-65535). The receiver operator decodes the 16-bit integer into an analog value in the range as follows:

where m is the 16-bit integer. The signal mappings and are properties of the receiver operator. The broadcast operator uses its own signal mapping properties ( and ) to encode the broadcast signal. If the receiver mapping properties are not the same as the broadcast mapping properties, the output of the receiver operator will not be the same as the input to the broadcast operator.
In order to associate a receiver operator to a particular network broadcast, the generic operator must be linked to a specific network channel in the physical hardware, and its signal name property must match the broadcast signal name exactly. Signal names are case sensitive---Design Pad considers the names "OilPressure", "oilPressure", and "OILPRESSURE" to refer to different signals.

User-Defined Properties:
Signal Name. A string label that identifies the broadcast signal that the receiver is "tuned" to. Design Pad associates this receiver operator in one schema with a broadcast operator in another schema that has the same signal name.
Maximum Broadcast Dead-Time. The period of time (in milliseconds) that may elapse before the receiver operator indicates that it has not received a broadcast signal (switches output to HIGH). Output remains LOW while the operator actively receives the broadcasted signal.
0% Mapping. The lower limit of the output signal range,
100% Mapping. The upper limit of the output signal range, .
Display Value Change of Value Output. This property determines if the error output pin is visible in the schema diagram. Design Pad issues a warning upon processing the schema when the pin is visible but not connected. The warning message is not issued when the pin is not visible (when this property is not checked).
Display Error Output. This property determines if the error output pin is visible in the schema diagram. Design Pad issues a warning upon processing the schema when the pin is visible but not connected. The warning message is not issued when the pin is not visible (when this property is not checked).

Change of Value Dead-Band. This parameter is applicable only to analog receivers. It determines the magnitude of the signal change that must be detected in order for output to declare that the signal has changed value. For example, if this property is set to 0.1, and the broadcast value changes from 39.50 to 39.58, the operator will declare that the value has not changed. If the value next changes to 39.62, the operator will declare that the value has changed (relative to 39.50). The next value change indication will not occur until the received broadcast signal is £39.52 or ³39.72.

Comments: None.

See Also: FairNET Broadcast