RS-232 timing diagram

RS-232 signaling

Typically individual ASCII characters are transmitted as a sequence of 8 bits bounded by a start bit and a stop bit, with a bit order of LSB first and MSB last.

Electrically the voltage swing is relatively high and polarity is inverse, so that a Logic level 1 is a low voltage between –3 V and –15 V, and a logic level 0 is a high voltage between +3 V and +15 V.

RS-232 is a low-speed standard for data transfer, with a baud rate of 9600 being most commonly used. The low speed and short bursts of data have the advantage that the receiver is able to synchronize using the start bit alone and therefore no addition synchronization clock line is required.

RS-232 decoding with PicoScope

RS-232 serial decoding is included in PicoScope as standard. The decoded data can be displayed in the format of your choice: In Graph, In Table, or both at once.

In Graph format shows decoded data in Binary, Hex, Decimal, or ASCII format, aligned with the analog waveform, on a common time axis. Decoded data can be zoomed and correlated with acquired analog channels to investigate timing errors or other signal integrity issues that are root cause of data errors.

In Table format shows a list of the decoded packets, showing data values with the packet start and stop times.

The PicoScope RS-232 decoder can also handle similar serial data standards such as RS-422, RS-485 and UART.