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Kepware Knowledge Base: Solution

Benchmarks for Serial-based Drivers

Last Update: 11/12/2018

Many factors can influence the rate that data is received from a serial device. Common factors include the baud rate at which it communicates, the rate at which it can process a request and respond, and how much it can process in one request. Most devices allow the requesting device/driver to request blocks of data, which is faster than requesting one item at a time. The general rule is that it takes approximately 1 msec to transfer 1 byte at 9600 baud, 2 bytes per msec at 19.2k baud, and so on. For example, a user was requesting 100 holding registers from a Modbus RTU at 9600 baud and it was able to respond instantly. It would take 8 bytes to request the data, and the response would take 205 bytes or a total of 213 msec to process the request. If a user was requesting a lot of data from the RTU, it could take several seconds to receive it all. For more information, refer to Optimizing KEPServerEX V5 Projects.