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© Sealevel Systems, Inc. 7406e Manual | SL9252 10/2022
Hardware Configuration
Address and IRQ selection
The COMM+4/232.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.
Clock Modes
The COMM+4/232.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.
Baud Rates
The following table shows some common data rates and the rates you should choose to achieve them
when using the COMM+4/232.PCIe.
For This Data Rate
Clock Prescaler
Choose This Divisor DLM:DLL
1200 bps
1
3255
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
