Assembly: Cognex.VisionPro.Comm (in Cognex.VisionPro.Comm.dll) Version: 87.0.0.0
| Exception | Condition |
|---|---|
| CogFfpInvalidOperationException | Thrown if the requested operation is invalid in the current state. |
Vision Systems often have an "online" and "offline" state. The exact meaning of what it means to be online and offline may differ depending on the particular vision system and application.
The NDM allows the vision system to communicate and synchronize its online/offline state with the remote device using the NotifyRunning and NotifyStopped(CogNdmStoppedCodeConstants) methods.
The vision system calls NotifyRunning to notify the remote device that the vision system is running or online.
The vision system calls NotifyStopped(CogNdmStoppedCodeConstants) to notify the remote device that the vision system has stopped or gone offline.
The vision system's current online/offline state is reflected in the high or low state of remote device's "Online" signal.
The remote device may also signal the running vision system to go offline. The remote device does this by asserting its "Set Offline" signal high. When the remote device raises the "Set Offline" signal high, the vision system receives the NDM OfflineRequested event.
The remote device may also signal the stopped vision system to return to its previous state. The remote device does this by setting its "Set Offline" signal low. When the remote device lowers the "Set Offline" signal, the vision system receives the NDM OfflineRequested event.
Your vision system code should handle the NDM OfflineRequested event. When your code receives this event you should examine the ReturnToPreviousState property of the event args to determine whether the remote device has signaled the vision system to go offline, or to return to the previous state.
Once the code in your event handler has made the necessary transition, be sure to call NotifyStopped(CogNdmStoppedCodeConstants), or NotifyRunning to notify the remote device of the new state of the vision system.