User manual

53
Serial Bus Analysis
soft menu key SYMBOL SIZE and the universal knob to se-
lect 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 al-
lows 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 sec-
tion of the control panel and choose the soft menu key SE-
RIAL BUSES. Then press the SOURCE button in the TRIG-
GER section and choose UART. This will only be availa-
bleifitwasconguredearlier.PresstheFILTERbutton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
respective symbol. If the input is hexadecimal, only the
entire symbol can be set to X. Use the soft menu key
SELECT SYMBOL to toggle between symbols.
❙ PATTERN: Offers additional options for UART trigger
settings. The soft menu key SYMBOL OFFSET and the
universal knob are used to select the number of irrelevant
symbols that proceed the pattern within the frame that
are relevant for the trigger event. Any value between 0 to
4095 symbols after the start bit may be entered. Use the
soft menu key NUMB. OF SYMB. to select the number of
Fig. 12.15: Page 2|2 UART BUS setup menu
Fig.12.14:Page1ofthemenutodeneaUARTbus
Fig. 12.16: Trigger menu UART data