Author: Sealevel
Category: Asynchronous Serial

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Sealevel USB serial adapters are supported by the SeaCOM driver, which includes a latency timer with a default setting of 16 msec. Decreasing this value reduces the amount of time a USB device buffers data before completing a write to the host computer, which increases the CPU overhead of the driver. A full USB device buffer is sent immediately without waiting for the timer to expire. Decreasing the latency timer can improve performance related issues and should reduce the overall latency of read cycles.

To access the latency timer, navigate to Windows Device Manager; expand the ‘Ports’ section and right-click on the USB to serial adapter listed. Click ‘Properties’ to open the device properties window. Click the ‘Ports Settings’ tab followed by the ‘Advanced…’ button. The ‘Latency Timer (msec)’ drop box is located in the ‘BM Options’ group on the left side of the window.

To avoid potential data loss, we do not recommend setting the latency timer below 4 msec. The latency timer does not affect the transmission of data from the host computer to the USB device.