Instructions

Table Of Contents
Protocol Analysis
R&S
®
Scope Rider RTH
199User Manual 1326.1578.02 ─ 15
RS-422. The UART uses only one line, or two lines for transmitter and receiver. The
R&S RTH can analyze one UART line.
Data transfer
The data is transmitted in words, also referred to as symbols or characters. Each word
consists of a start bit, several data bits, an optional parity bit, and one or more stop
bits. Several words can form a frame, or package. The end of a frame is marked by a
pause between two symbols.
[Data8]
[Parity]
Stop[Data7][Data6][Data5]
Data4Data3Data2Data1Data0
Start
Figure 9-19: Bit order in a UART word (symbol)
The start bit is a logic 0.
The stop bits and the idle state are always logic 1.
The UART protocol has no clock for synchronization. The receiver synchronizes by
means of the start and stop bits, and the bit rate that must be known to the receiver.
Trigger
The R&S RTH can trigger on specified parts of UART serial signals:
Start bit of a word
Frame start
Data pattern
Parity error
Stop error
Break
9.4.2 UART Configuration Settings
Access: "Bus" menu > "Bus Protocol" = "UART" > "Config"
UART/RS-232/RS-422/RS-485 (Option R&S RTH-K2)