User Manual DDS200 Digital Demodulation System 070-9952-00

Appendix F: Remote Control via RS-232-C InterfaceDTRGNDDSRRTSCTS(Data terminal ready),Output (logic ‘0’ = active); controller informs EFA via DTRthat RS-232 interface is active. DTR remains active as longas interface is switched for remote control.(Ground),Interface ground connected to instrument ground.(Data set ready),Input (logic ‘0’ = active); DSR not used in EFA.(Request to send),Output (logic ‘0’ = active); EFA informs the controller viaRTS that it is ready to accept data. If RTS is active, EFA isready to receive a character.(Clear to send),Input (logic ‘0’ = active); CTS controls the data output ofEFA. If CTS is active, EFA is ready to output data.Transmission ParametersTo ensure error-free and correct data transmission, the parameters of the DDS200and the controller must be set to the same values. Setting is made in the SETUP \REMOTE \ RS232 menu. Parameters in bold type indicate the basic settingmade at the factory.Transmission rate The DDS200 has5 different baud rates:(baud rate) 1200, 2400, 4800, 9600, 19200.Data bitsStart bitParity bitStop bitsData are transmitted in 7- or 8-bit ASCII code. The LSB(least significant bit) is the first bit transmitted.Each data byte begins with a start bit. The trailing edge ofthe start bit indicates the beginning of the data byte.A parity bit can be transmitted for error correction. There arethree possibilities: no, even or odd parity. In addition, theparity bit can be set to logic ‘0’ or logic ‘1’.The transmission of a data byte can be terminated by one ortwo stop bits.01 02 03 04 05 06 07 08 09 10 11StartbitData bitsParitybitStop bitsFigure F–1: Transmission of character A in 7-bit ASCII code, even parity, 2 stop bitsDDS200 Digital Demodulation System User Manual F–3