National Instruments PCI-8430, Manual

Page: 194 / 237

What is the relationship between bits per
second, throughput, and bus utilization?
The term bits per second (bps) refers to the bit rate of data transfer, with
1/bps being the length of time required to transmit one bit.
Throughput is the actual data transfer measured by
amount of data transmitted time required to transmit
Bus utilization is the percentage of time that the serial bus is actively
transmitting data. Because a wide range of factors such as flow control,
processor latency, and device architecture can affect serial performance,
bus utilization often is not 100 percent. In addition, there is overhead
associated with serial communication in the form of start bits, stop bits,
and parity bits. This overhead reduces the throughput by 20–30 percent.
Thus, the actual data throughput can be considerably less than the bits
per second setting.