Perle Systems Adaptors - Manual (Page 43)

FAST Serial Adaptors User Guide
Installing under Windows 2000/XP/Server 2003/Vista/Server 2008
Page 43
Chapter 2 Installing drivers and host cards
10.In the FIFO Settings page, set the FIFO buffer levels using the parameters detailed in the
next table.
11.Within the Serial Port properties window, click on the OK button to save changes and
close the window.
The configuration process is now complete.
Hint
To restore the default settings, use the Restore Defaults button.
Parameter Description
Tx FIFO Limit Sets the overall size of the Transmit FIFO buffer.You use this
when you want to restrict the size of the buffer in order to control
the data flow. This is useful when your application requires you
to send small amounts of data but needs acknowledgement
that the data has been sent.
For example, if your application is designed to receive 4 bytes
at a time, a larger value of say 16 would time out.
Permitted values for a FAST card are 1 to 64.
Tx FIFO Trigger Level Sets the level at which the com port Transmit FIFO buffer is
filled with data each time a request for more data is made.
For example, if set to 16 bytes you get 16 bytes at a time when
driver requests data.
Permitted values for a FAST card are 8 , 16 , 32 and 56 .
Rx FIFO Trigger Level Sets the level at which the com port Receive FIFO buffer is filled
before the data is passed on to an application.
For example, if set to 16 bytes, 16 bytes of data are
accumulated at a time before data is passed on to an
application. The FIFO trigger will also time out if the level is not
achieved within two character periods of the last byte received.
Permitted values for a FAST card are 8 , 16 , 56 and 60 .
High Flow Control
Threshold Sets the level at which data flow is suspended.
If the limit is exceeded, the driver will stop collecting data.
For FAST, value is read only , set automatically from FIFO
trigger level.
Low Flow Control
Threshold Sets the level at which data flow is resumed.
If the low flow threshold is exceeded, the driver requests more
data.
For FAST, value is
read only , set automatically from FIFO
trigger level.