©Sealevel Systems, Inc.
SL9219 – 04/2013
7804e Manual
6
The Ultra COMM+8.PCIe is automatically assigned I/O addresses and IRQs by your motherboard
BIOS or by a ‘Plug-n-Play’ Operating System. Adding or removing other hardware or moving the
adapter to another slot may change the assignment of I/O addresses and IRQs.
The Ultra COMM+4.PCIe derives a 62.5MHz clock from the PCI express link which is divided by
a 8 bit clock prescaler and a 16 bit clock divisor to provide a wide range of possible baud rates.
Note that there are many combinations that can give the same result (e.g. Prescaler=1 and
Divisor = 8, Prescaler =2 and Divisor = 4, or Prescaler=8 and Divisor = 1). As long as the
calculated data rate is /- 2% you should communicate fine.
The following table shows some common data rates and the rates you should choose to achieve
them when using the ULTRA COMM+8.PCI
For This Data Rate
Clock Prescaler
Choose This Divisor DLM:DLL
1200 bps
1
3255
2400 bps
1.625
1001
4800 bps
1.750
465
9600 bps
1.875
217
19.2K bps
1.5
136
38.4K bps
1.75
588
57.6K bps
1.825
37
115.2K bps
1.875
18
230.4K bps
1
17
460.8K bps
2.125
4
921.6K bps
2.125
2
