TTY SILOTIME

TTY_SILOTIME is a system parameter that defines the interval at which the DMF32 hardware polls the input silo for received characters. The DMF32 asynchronous terminal controller can delay the generation of a single input interrupt until multiple characters have accumulated in the input silo. TTY_SILOTIME specifies the number of milliseconds that the characters are allowed to accumulate prior to the generation of an input interrupt by the hardware. NOTE The remainder of this discussion is of interest to customers who use Digi Edgeport hardware. TTY_SILOTIME controls latency, trading throughput and system overhead for latency. The default value for TTY_SILOTIME is 8. This value is multiplied by 100 and is used as a count of the number of times to send a query to the device for more data after a character transmit or receive is performed. If no input (or no subsequent output) is seen after 800 responses to the query, the driver stops sending queries to the device and waits for an input interrupt. Reducing the TTY_SILOTIME value allows the device to buffer more data, with slightly higher latency. Increasing the value of TTY_SILOTIME makes the device more sensitive to latency but decreases buffering and overall throughput; it also adds more system and USB overhead. Setting TTY_SILOTIME to zero causes the driver to send input queries to the device continually. This setting causes the lowest latency, the highest system overhead, and the lowest throughput possible.