TOP Server ControlLogix Warning Message: "Project online edit detected. Currently using Symbolic Addressing"

When using logical mode, the driver has to get a mapping of tag names to memory locations from the PLC. When someone updates the PLC program, that mapping could change in the PLC, so the driver has to request an updated mapping. This is part of the tradeoff to obtain the faster performance of logical protocol mode.  While that request for an updated map from the PLC is occurring, the driver will switch back to symbolic mode, where tag names are passed in the requests to the PLC instead of using the faster memory locations, to keep communications going with the PLC as best as possible. There will be a small period of time, for safety reasons, where communications are paused to insure that the driver does not read from or write to an incorrect location. The time it takes to complete the request is a function of the size of the PLC project, the PLC processor speed, loading on the PLC processor from it's main job of control, and network speed.

Once the request for mapping has been completed, the driver will go back to logical mode, as you can see in the example below. We have blurred out user specific names in this example for confidentiality reasons, but there were 2 connections that had changes (different length of blurred out areas) and you can see the roughly 3 second pause for safety while the updates made in the PLC were applied:

 

For small projects, you may not even notice a performance change. With large projects you will likely see slower performance, and possibly some timeout errors as well, depending on how fast you are polling for data.  

The message is posted as a warning because this process does not stop communication or indicate a failure, but provides you with history of what was happening in the system, in case a user later complains about slow performance during a certain time period.