User manual

PCI-ICM422/2(4) and 485/2(4) Manual
Page 5-2
Manual MPCI-ICM4S.F1b
When the BAUD jumper is in the X1 position, the UART clock frequency is 1.8432 Mhz. When the
jumper is in the X4 position, the clock frequency is 7.3728 MHz. The following table lists popular
divisor frequencies. Note that there are two columns to consider depending on the position of the
BAUD jumper.
Baud Rate Divisor
x1
Divisor
x4
No tes: Max Diff. Cable Length *
460800 N/A 1
230400 N/A 2
153600 N/A 3
115200 1 4 375 feet
57600 2 8 660 ft
38400 3 12 920 ft
28800 4 16 1165 ft
19200 6 24 1620 ft
14400 8 32 2050 ft
9600 12 48 Most common industrial
speed
4000 ft
4800 24 96 4000 ft
2400 48 192 4000 ft
1200 96 384 4000 ft
* Recommended maximum distances for differentially driven data cables (RS422 or RS485) are for
typical conditions.
Table 5-1: Baud Rate Divisor Values
In C, the code to set the chip to 9600 baud is:
outportb(BASEADDR, 0x0C);
outportb(BASEADDR +1,0);