Connect Tech BlueStorm/Express User Manual
Revision 0.15
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Advanced Port Settings
Use FIFO Buffers
For performance reasons, it is preferred that the FIFO buffers on the UART be used. When the
Use FIFO Buffers
option is enabled, the UART will be more efficient at moving data. Other
functions such as flow control will be managed by the UART when this option is enabled.
In some cases you may need to disable the FIFO buffers. This issue usually happens when the
connected equipment cannot deal with data that is sent with minimal gaps between characters, or
cases where the EscapeCommFunction (PortHandle, SETXOFF) function is used.
Receive and Transmit FIFO Settings
These sliders adjust the size of UART FIFO levels used by the CTI PCI Express UART serial
ports. You obtain more buffering the further you move the slider to the right. This results in higher
throughput, and lower load on the system. Note that high buffer levels can cause communication
problems with some applications.
Usually the best setting is to have the receive buffer set at one notch below the highest setting and
the transmit buffer at the highest setting.
Software Settings for RS-422/485
RS-422/485 ports have the following options available:
Full Duplex
In this mode, TxD & RxD are active all the time. This mode is typically used in point-to-point
situations much like RS-232. RTS and CTS can be used along with the data signals.
Half Duplex
In this mode the TxD line driver is only enabled when data is transmitted, and RxD is disabled
when data is being transmitted. This mode is typically used in either point-to-point (2 wire)
connections OR in multi-drop (2 wire) bussed connections. CTS and RTS are not usually used
with this configuration.
Multi-Drop
In this mode the TxD line driver is only enabled when data is transmitted and RxD is enabled all
the time. This mode is typically used in multi-drop (4 wire) connections. RTS and CTS are not
usually used in this configuration.
Note: RS-485 Options are available if your BlueStorm/Express card is built or configured
as RS-485, but does not mean the port is currently set this way. Check your card and
ensure the jumpers are configured for RS-485 operation before changing the software
setting.
