User manual

Connect Tech BlueStorm/Express User Manual

Revision 0.02

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 blow 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.