User manual

Reference182
Copyright © 2007-2013 Pico Technology Ltd. All rights reserved.psw.en r32
9.6.4
RS232/UART protocol
You can decode RS232 (UART) data using the serial decoding feature built into
PicoScope.
About RS232
RS232 is the serial data standard used by UARTs (Universal Asynchronous Receiver/
Transmitters) in the "serial" or "COM" ports once commonly found on computers. It
was developed in the 1960s for connecting modems to terminals. The full standard
uses a voltage swing of ±12 V, larger than most other standards. The simplest RS232
connection consists of two signals: Rx (receive) and Tx (transmit).
The in-window view of the data looks like this:
The columns in the data table are as follows:
Column
Description
No.
Serial number of the packet (decimal). If Accumulate mode is
off, this counts from the start of the selected waveform. If
Accumulate mode is on, this counts from the start of the first
waveform in the waveform buffer.
Packet
Packet type: all packets in this format are classified as Data.
Start Bit
If present, this is the fixed "1" bit at the start of the word.
Data bytes
Contents of data packets.
Parity Bit
The error-correction bit, if present, at the end of the word.
Stop Bit
If present, this is the fixed "1" bit at the end of the word.
Error
Indicates whether there was a data error.
Start Time
Time according to PicoScope timebase at start of frame.
End Time
Time according to PicoScope timebase at end of frame.
Packet Time*
The duration of the packet (End Time – Start Time).
Min Voltage*
Minimum voltage.
Max Voltage*
Maximum voltage.
Voltage Delta*
Voltage range of the signal (Max Voltage – Min Voltage).
* Display of these items is toggled on and off by the Statistics button.