User manual

53
Serial BUS Analysis
menu key DATA SOURCE to select the desired channel via
universal knob. The soft menu key ACTIVE can be used
to determine if the data transferred to the BUS are active
high (High = 1) or active low (Low = 1) (for RS-232, choose
Low). Use the soft menu key SYMBOL SIZE and the uni-
versal knob to select a value between 5 bit to 9 bit for the
bits that form a symbol. Another setting can be selected
via soft menu key PARITY. Parity bits are used to detect
errors during a transmission. The soft menu PARITY offers
the following options:
None: Use no parity bits
Even: The parity bit is set to “1” if the number of ones in a
specicsetofbitsisuneven(withoutparitybit)
Odd: The parity bit is set to “1” if the number of ones in a
specicsetofbitsiseven(withoutparitybit)
ThebottomsoftmenukeySTOPBITSallowsyoutodene
the length of the stop bit (1 = single, 1.5 = 1 1/2 or 2 =
double).
On page 2|2 of the UART BUS setup menu, you can se-
lect the BIT RATE (symbol rate) via universal knob in the
CURSOR/MENUsection.Thebitratedeneshowmany
bits are sent per second. The soft menu key BIT RATE
allows you to select standard numeric values. Press the
softmenukeyUSERifyouwishtodenecustomizedra-
tes via universal knob or numeric input (KEYPAD button).
The IDLE TIME describes the minimum time between the
stop bit of the last data and the start bit of the new data.
Thesolepurposeoftheidletimeistodenethestartofa
transmission and consequently the exact start of a frame
(one or more symbols, most commonly bytes). Only this
information can guarantee correct decoding and triggering
(regardless of the trigger type). A start bit within the idle
time will not be recognized. You can enter the value via
universal knob in the CURSOR/MENU section or numeric
input (KEYPAD button).
12.6.2 UART/RS-232 BUS Triggering
After the BUSconguration,itwillbepossibletotrigger
on various events. Press the TYPE button in the TRIGGER
section of the control panel and choose the soft menu
key SERIAL BUSES. Then press the SOURCE button in
the TRIGGER section and choose UART. This will only be
availableifitwasconguredearlier.PresstheFILTERbut-
ton in the TRIGGER section of the control panel to list all
available UART trigger conditions:
START BIT: Sets the start bit as trigger event. The start
bitistherst0bitthatsucceedsastopbitoridletime.
FRAME START: Denestherststartbitafteridletime.
SYMBOL<N>: AssignsapredenedN-thsymbolas
trigger event.
ANY SYMBOL: The soft menu ANY SYMBOL allows you
todeneanysymboltotriggeron.Thesymbolcanbe
located anywhere within a frame. The serial bit sequence
(PATTERN INPUT) can be entered as binary or
hexadecimal value. If you choose the binary input, the soft
menu key SELECT BIT and the universal knob allow you to
select which individual bits within the data are to be
edited. Select the option STATE to assign a logic state to
each bit (High = H = 1, Low = L = 0 or X = don’t care).
ThestateXdenesanystate.Ifyouchoosethe
hexadecimal input, the soft menu key VALUE and the
universal knob allow you to set the value for the
Fig.12.13:Page1ofthemenutodeneaUARTBUS
If the option R&S®HOO11 resp. the voucher R&S®HV111 is ins-
talled, it it only possible to select analog channels as source. If
the option R&S®HOO10 resp. the voucher R&S®HV110 is installed,
both analog and digital channels are available as source.
Fig. 12.14: Page 2|2 UART BUS setup menu
Fig. 12.15: Trigger menu UART data