WinCC Unified – Simple Sample – Communication live bit monitoring

Hi,

“Simple Samples” are small projects that demonstrate simple features. The target is giving a quick overview about the theme and be used as start point for related discussions. Follow there are a short description and the configuration main steps.

Despite of all diagnostic resources of TIA, sometimes it is interesting have a bit that shows to the HMI if the PLC is running ok or, a bit to that shows to the PLC that the HMI/SCADA is running.

Depending on the case, this bit should not show if the communication is ok, but also that informs that the programing is running and running in a specific condition (e.g. “not hanged”). This type of the monitoring is donning e.g. by a live bit (some signal that changes on the time to prove the health of the system).

In this simple sample, there are two live bit monitoring: one from controller to HMI and other from HMI to controller. In both cases an integer variable is incremented and the partner checks if it changes during a time interval. As result an OK bit is generated.

In the PLC it is done by a single block. In the WinCC Unified (as didactical proposes) is done by two separate time triggered schedule tasks.