Quatech Asynchronous Communications Adapter DSC-200/300 User Manual

Quatech Asynchronous Communications Adapter DSC-200/300 User Manual Manual pdf 12 page image

2.4.2 Force High-Speed UART Clock (X2, X4, or X8, J10-J12)These jumpers force an increase of the UART input clock frequency by a factor oftwo, four, or eight. This feature can allow legacy software to use baud rates above115,200 bits per second. It is also useful if the serial port device driver does not directlysupport setting the higher baud rates through the Options Register (see page 10).If one of these jumpers is applied, it overrides any value written to the OptionsRegister to set the clock multiplier by software. The effective baud rate will be eithertwo, four, or eight times the value for which the UART itself is programmed.The factory default is none of these jumpers applied, which allows for softwarecontrol of the clock multiplier via the Options Register. The Options Register powerupdefault is for a standard times-1 clock of 1.8432 MHz for compatibility with standardserial ports.SPADX2X4X8J10J11J12J13Force times-eight clockBaud rates up to 921.6 kbpsSPADX2X4X8J10J11J12J13Force times-two clockBaud rates up to 230.4 kbpsSPADX2X4X8J10J11J12J13Factory defaultsoftware controlSPADX2X4X8J10J11J12J13Force times-four clockBaud rates up to 460.8 kbpsFigure 5 --- Clock multiplier jumper optionsQuatech DSC-200/300 User's Manual 12