User Manual

Protocol Analysis
R&S
®
Scope Rider RTH
181User Manual 1326.1578.02 ─ 08
Table 8-3: Color codes of decoded SPI signals
Color, display element Description
Green brackets [...] Start and end of frame
Cyan comb Data words
Red Error, or insufficient frame (end of acquisition before decoding has been
completed)
In "Protocol" mode, decoded data is shown in tabular form.
Table 8-4: Content of the protocol table for decoded SPI signal
Column Description
# Frame index
Frame Start Time of frame start
MOSI <x> bit [format] Value of the MOSI data word. The data format is selected in the "Bus"
menu. The column header indicates the selected word length.
MISO <x> bit [format] Value of the MISO data word. The data format is selected in the "Bus"
menu. The column header indicates the selected word length.
State Overall state of the frame.
"Incomplete" indicates that the frame is not completely contained in the
acquisition. Change the time scale to get a longer acquisition.
Remote commands are described in Chapter 14.11.3.3, "SPI Decode Results",
on page 389.
8.4 UART/RS-232/RS-422/RS-485 (Option R&S RTH-K2)
8.4.1 UART Interface
The Universal Asynchronous Receiver/Transmitter UART converts words of data into
serial data, and vice versa. It is the base of many serial protocols like of RS-232 and
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 8-13: Bit order in a UART word (symbol)
UART/RS-232/RS-422/RS-485 (Option R&S RTH-K2)