TOP Server Connectivity for a Yaskawa U84 PLC

The TOP Server Yaskawa Suite will allow you to connect to your Memobus Serial Yaskawa U84. You will need to use the Yaskawa MP Serial driver in the suite, as that is the driver that supports Memobus Serial.  While this driver doesn't have the U-type of PLC as a choice, you can choose GL as a model type, since the only difference between the two is the addressing.  The GL series has the same addressing as the MP series but also supports constant registers.

Documentation for the U84 indicates that it uses standard Memobus Protocol and addressing, so this driver should have no trouble communicating with your device.  The U84 documentation can be found here.