B&B Electronics 1939STB manual RS-232 Baud Rate Change cont’d

RS-232 Baud Rate Change - cont’d.

All baud rates are entered as hex numbers. To determine the decimal divisor use the following formula. The decimal number must be converted to hexadecimal before entering the number into byte 6 and 7. Baud rates faster than 57,600 are not supported.

UART clock = 7,372,800 Hz

Decimal Divisor = Clock frequency (7,372,800)

Baud output x 16

If you want a baud rate output of 300 baud:

Decimal Divisor = 7,372,800 300 x 16

Decimal Divisor = 1536 = 600 hex

Baud 1= 00

Baud 2= 06

Programming a baud rate change to 300 baud, 1 stop bit, 8 bit data, no parity.

Table 13. Baud Rate Setup

Byte	Byte	Byte 3		Byte 4		Byte 5	Byte 6	Byte 7
1	2	Nibble 2	Nibble 1	Nibble 2	Nibble 1	UB3	Baud 1	Baud 2
81	21	0010	0011	0000	0010
81	21	23 hex		02 hex		03 hex	00 hex	06 hex

Table 13 is set to produce a baud rate of 300, 1stop bit, an 8 bit data word, and no parity.

10	1939STB4600 Manual
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