Vision Systems VScom 200E PCIex Instrukcja Użytkownika Pobierz pdf (Strona 30)

4 Windows Driver

Receive Trigger Level The time when the UART generates an interrupt for received data. It deﬁnes

the amount of data necessary to do this. With the 16950 you may select any value from 1

to 128. Other types allow only certain values. Higher values increase performance, lower

values decrease possibility for loss of data. As a reference: the usual value for a 16C550A is

8, leaving space for 8 more bytes to receive.

Transmit Trigger Level The time when the UART generates an interrupt for sent data. When the

transmit FIFO contains less data than this, the interrupt is issued. This value is not available

with all emulations. Higher values make a smoother transmission of data, but increase the

system load.

Transmit Buﬀer Length The amount of data sent to the UART when the transmit FIFO is empty.

This is a complete software item. The value ranges from 1 to the FIFO size of the emulation.

Higher values increase transmission performance. The typical value here is 16, the FIFO size

of a 16550. This value must not be less than the Transmit trigger level. CAUTION: external

hardware - such as a modem - must be able to handle this blocksize, very old systems may

require to reduce this parameter to ‘1’.

Enable TCR The 16C950 UART used on the H-series cards has some hardware option to get very

high bit rates, up to 3.6 Mbps. Of course these bit rates can not be used on RS 232, but

there are other advantages. The maximum serial speed is raised, so there are more possible

bit rates available in the usual range of RS 232 transmission. This allows to use some more

rather unusual settings for transmission rates, some special hardware may require. Possible

products with RS 422/485 line drivers can use such high bit rates.

Since this option may reduce the transmission accuracy in certain environments, it is disabled

by default.

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Vision Systems VScom 200E PCIex Instrukcja Użytkownika Strona 30