Writing data can be a very important task in your application. Depending on the communication settings and the response time of the connected device, the OPC client application may send write requests to the PLC faster than the data can be transferred. In this case, only the last write request is processed and sent to the PLC.
In certain instances, e.g. when using sliding switches in HMI applications, it may be important for every write request to be processed and sent to the PLC. In such cases, select the check box "Process all write requests".
If more write requests are sent to the server than the server can send to the PLC, it may negatively impact the transfer time between server and PLC.