B&B Electronics RS-232 to J1939 Converter CE 1939STB - Manual (Page 12)

10 1939STB4600 Manual
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B&B Electronics Ltd – Westlink Commercial Park – Oranmore, Galway, Ireland – Ph +353 91 792444 – Fax +353 91 792445
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 3 Byte 4 Byte 5 Byte 6 Byte 7 Byte
1 Byte
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.