Operating Manual R&S SMIQ - Volume 1 - Rohde & Schwarz

SMIQAsynchronous Interface SERDATAA.3 Asynchronous Interface SERDATAThe SERDATA interface on the rear of SMIQ serves for the asynchronous serial transmission ofmodulation data. It is a RS-232-C interface with the following characteristics:• Data transmission to SMIQ in one direction only via RxD line (Receive Data).• Selectable data rate in menu UTILITIES-SYSTEM-SERDATA-BAUDRATE. The highest baud rate is115 200.• Hardware handshake only via RTS line (Request to send). With RTS, SMIQ is ready to receive data.After inactivating RTS, SMIQ can receive 32 bytes at max.• Data transmission with start bit, 8 data bits (= 1 byte), stop bit. A parity bit is not used. The mostsignificant bit of each modulation symbol has to be transmitted at first.Note:The baud rate has to be selected at least 25% higher than the bit rate of the digitalmodulation. If SMIQ has not enough data, the error message "Data underrun" will beissued in the status line.Connection between SERDATA and the external RS-232 data source is via a so-called null modemcable with crossed data and control lines.1125.5555.03 A.7E-7