The workspace maintains the configuration information for each FairNET (e.g., the latency time for critical broadcasts, the devices assigned to each network, the broadcast signals that traffic each network, etc.). You can access the network configuration by right-clicking on a logical network icon in the workspace and selecting the Properties item from the drop-down menu.
Figure 9.21. Configure Network Dialog Settings Panel
Using the Configure Networks dialog box shown in Figure 9.21, you can view information about FairNET settings, general information, and signal data for the selected network. Use the left pane of the dialog to select the desired information set.
The FairNET Settings selection provides the following information:
Network ID. A unique identifier generated by Design Pad when the network is created. FairNET uses this identifier to determine if a station belongs on the network. (When a controller is physically connected to a network, its Network ID must match that of other stations on the network.)
Network Version. An integer value that tracks changes in a network's configuration. FairNET uses this parameter to maintain a consistent set of configuration files for all stations on a network.
Critical Broadcast Latency Time. FairNET supports deterministic and nondeterministic messaging. Deterministic messages are reserved for the most critical signals in a networked control system. A FairNET network guarantees that these signals are transmitted at regular intervals. This parameter specifies the length of the interval between successive critical message transmissions (expressed in milliseconds). By default, Design Pad sets this value to 100 milliseconds (i.e., by default, critical broadcast messages are transmitted every 100 milliseconds.)
The General Info section provides the following information:
Figure 9.22. Configure Network Dialog General Info Panel
Network Name. The name of the network (displayed in the Network View tab of the workspace window).
Interfaces Assigned to this Network. Information about each device assigned to the network, including:
Interface. The name of the device (controller, OPC server, etc.)
Station ID. A Design Pad generated integer value that uniquely identifies each node in network. FairNET uses this parameter to determine the source and destination of a given communication message.
Station Type. FairNET uses a master/slave architecture to arbitrate communication messages. One device on the network, the master device, coordinates all the network traffic. All other devices are slaves to the network master -they transmit information on the network only when prompted to do so by the master device. Design Pad automatically selects which station on the network will serve as the master.
Master Rank. Every station in a FairNET network has the capacity to function as the network master. If the master goes offline, one of the remaining slave devices on the network will automatically take on the master role. This parameter determines which device on the network assumes the master role (the active station with the lowest master rank).
The Signals section provides the following information:
Figure 9.23. Configure Network Dialog Signals Panel
Signal Name. The name of the broadcast signal (corresponds to a broadcast operator in a schema).
Source Station ID. The Design Pad generated station identifier for the node that transmits the broadcast signal (as shown in the General Info section).
Type. The FairNET network broadcast operator type: analog broadcast, digital broadcast, network-enabled A/M Button
Critical? FairNET supports deterministic and non-deterministic messaging. Deterministic messages are reserved for the most critical signals in a networked control system. A FairNET network guarantees that these signals are transmitted at regular intervals. FairNET also transmits non-critical messages at regular intervals but does not guarantee that it will always do so---occasionally, during periods of heavy network traffic, some non-critical message transmissions may be delayed. This parameter indicates if the given broadcast signal is or is not critical.
Latency. The time interval (in milliseconds) between successive broadcast transmissions. All critical broadcasts in a network have the same latency time (it is a property of the network). Non-critical broadcast message latency times can vary from one station to another (the non-critical broadcast message latency time is a property of the network node).
0% Map. The lower limit of the broadcast signal range.
100% Map. The upper limit of the broadcast signal range.
Initial Value. The initial broadcast signal value.
