©Sealevel Systems, Inc.
SL9249 – 12/2013
7802e Manual
7
Hardware Configuration
The COMM+8.422.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 COMM+8.422.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 COMM+8.422.PCIe.
For This Data Rate
Clock Prescaler
Choose This Divisor DLM:DLL
1200 bps
3.625
898
2400 bps
3.625
449
4800 bps
1.875
434
9600 bps
1.875
217
19.2K bps
1.375
148
38.4K bps
1.375
74
57.6K bps
22.625
3
115.2K bps
1
34
230.4K bps
1
17
460.8K bps
2.125
4
921.6K bps
2.125
2
