Impulse SIO4-104.485 (3543) - Manual (Page 6)

© Sealevel Systems, Inc. - 4 - SIO4-104.485 User Manual
Clock Modes
The SIO4-104.485 utilizes a 14.7456 MHz oscillator. This is eight times faster than the standard
COM: port oscillator, which typically is 1.8432 MHz. This allows the adapter to achieve a
maximum data rate of 921.6Kbps. The following sections outline the baud rate calculations and
instructions for achieving your desired baud rate.
Baud Rates and Oscillator value
The following table shows some common data rates and the rates you should choose to achieve
them when using the SIO4-104.485. If the O/S of choice is Windows 95/98/ME/2000/NT/XP, the
oscillator value (14.7456 MHz) should be entered into the ‘Advanced Tab’ on 95/98/Me/2000/XP
Device Manager applet. Typically this is done automatically when the Sealevel Software driver is
loaded.
When using Windows NT, the ‘Advanced Ports’ applet in the Control Panel should be launched
and the oscillator value entered manually in the ‘Advanced’ tab, or all data rates will be eight (8)
times the selected rate. For example if a data rate of 19.2Kbps is selected, the actual data rate will
be 153.6Kbps.
When using any other OS (i.e. Linux, or QNX) the following table should be used.
For this Data Rate Choose this Data Rate
1200 bps 150 bps
2400 bps 300 bps
4800 bps 600 bps
9600 bps 1200 bps
19.2K bps 2400 bps
57.6 K bps 4800 bps
115.2 K bps 14.4K bps
230.4K bps 28.8K bps
460.8K bps 57.6 K bps
921.6K bps 115.2 K bps
If your communications package allows the use of Baud rate divisors, choose the appropriate
divisor from the following table:
For this Data Rate Choose this Divisor
1200 bps 768
2400 bps 384
4800 bps 192
9600 bps 96
19.2K bps 48
38.4K bps 24
57.6K bps 12
115.2K bps 8
230.4K bps 4
460.8K bps 2
921.6K bps 1