3
Windows Driver
Transmit control Enable
This enables the automatic control when sending data. If the receiving
device sends a stop (Xoff) signal, transmission is halted. When a continue (Xon) signal is
received, transmission continues. This reduces the probability of sending too much data to
the receiver. This does not need any processing by the main processor.
Transmit control Xon/Xoff Character
The special characters acting as continue and stop signals
as above. Normally stop (Xoff) is a ^S (dec: 19, hex: $13), continue (Xon) is a ^Q (dec: 17,
hex: $11). You should not change these values.
Receive control Enable
This enables the automatic control when receiving data. When to much
data is received and not read by the processor, the UART generates a stop signal to the other
side. When enough data is read by the processor, the UART generates a continue signal.
Receive control Xon/Xoff Character
Same function as Transmit control above. Even when it is
possible to use other values than above, we strongly recommend to use the standard values.
Receive control Triggers Xon
The level when the UART generates the continue signal. When the
processor reads the received data, the amount remaining in the UART will eventually fall
below this limit. At that time the continue signal is issued to the other side.
Receive control Triggers Xoff
The level when the UART generates the stop signal. When this
amount of data is received and stored in the FIFO, the UART issues the stop signal to hold
further transmission by the other side. This value must be higher than the Xon Trigger.
Depending on the global situation (processor speed, system load, transmission parameters,
transmitting device, ...) possible values can be: 32 (quarter of FIFO) for Xon and 64 (half)
for Xoff.
February 2010
VScom PCIex Card User Manual
28