Chapter 3 Demo Board Applications
RIGOL
User’s Guide for DS6000 Demo Board 3-35
3.3 Digital Signal Applications
3.3.1 RS232/UART Signal
1.
RS232 Protocol Explanation
The start bit is always high level; the data bits is always 6bits, 7bits or 8bits. It is fixed at 8bits in
this Demo board;
By default, the data polarity is negative (namely high level stands for logic 0 and low level stands
for logic 1);
Check bit usually contains odd check, even check and none. For this Demo board, RS232 signal
does not have check bit;
Stop bit is always 1bit, 1.5bits or 2bits. For this Demo board, the stop bit of RS232 signal is 1bit.
2.
Signal Explanation
Signal Output Pin:
RS232_TX
Rate: 9600bps; Data: RIGOL DS6000; Frame structure: 1bit start bit+ 8bits data bits+ 1bit stop
bit;
LSB output; negative polarity, none (check bit)
3.
Functions
RS232 trigger, RS232 decoding
4.
Demonstration and Result
Connect the signal output pin RS232_TX and GND to CH1 of the oscilloscope properly using the
probe;
Set the trigger type to “RS232”, the signal source to “CH1”, the trigger condition to “Start”, the
baud rate to “9600bps” and the trigger mode to “Auto”; adjust the vertical position and trigger
level to appropriate values to make the oscilloscope trigger stably;
When the oscilloscope is in T’D mode, set the decoding type to “RS232”, TX to “CH1”, RX to
“OFF”, the polarity to “-”(negative), the data bits to “8”, the stop bit to “1 bit”, the even-odd
check bit to “None”, the ary to “ASCII” and TX threshold to 1.36V. Set the BUS status to “ON”
and the demonstration result is as shown in the figure on the next page.
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