Linking Receivers to Broadcasts

The FairNET broadcast and receiver operators described in section 9.3.1 are generic hardware operators that must be linked to a specific communications channel on FairNET enabled device. This process is similar to the process on connecting a generic analog input operator in a schema to a physical analog input resource in a module (see section 4.5).

The schema fragments above are populated with broadcasters and receivers in anticipation of sharing data on a FairNET RS-485 network. LOCALdc.scm contains two analog broadcast operators Temperature and Pressure, as well as a digital broadcaster called LocalStop. It is prepared to receive a digital signal on RecRemoteStop. Conversely, REMOTEdc.scm contains two generically named analog receivers and a digital receiver called RecLocalStop, as well as a digital broadcast operator called SendRemoteStop. Next we will describe how to link these broadcast and receive operators to network resources so data may be exchanged between the two nodes.

Right click on the analog broadcast operator and select the Connect to Hardware option (Figure 9.13). The dialog in Figure 9.14 allows connection to the RS-485 layer on the node's NIM-1 since that is the hardware which supports the broadcast. Once the broadcasters are connected to hardware, turn the focus to REMOTEdc.scm. Right click on a receiver operator to connect it to a hardware resource. The connection dialog in Figure 9.15 appears, presenting a pulldown menu of broadcasters from which you may choose to receive the appropriate signal for this operator. Choose signals for each receiver in the schema. The dialog will only present analog signals in its list for analog receivers and digital ones for digital receivers. Be sure to name the broadcast operators descriptively so choosing which one is appropriate for a specific receiver is obvious.

Figure 9.13. Connecting a Broadcast Operator to a Hardware Resource

Figure 9.14. Selecting the Network for a Broadcast Operator

Figure 9.15. Associate a Receiver with the Appropriate Broadcast Operator