There are nowadays cheap logic analyzers (like Saleae Logic and USBEE) that can easily record many channels of fast changing digital signals and even decode the serial data on the line. Those would be ideal tools for serious debugging of RS-232 signals. But those devices have one downside: they are designed only for TTL (5V) and LV-TTL (3.3V) level logic signals. Standard RS-232 signal levels (typically +3..15V and -3..15V, but can be up to +-25V) are too much for those logic analyzers. Connecting logic analyzer directly to RS-232 signal will most probably damage the hardware. So I need some form of converter that can convert RS-232 signals to TTL signals.
I ended up building my circuit inside a RS-232 Mini Tester I had lying around. This construction gave me nice boxed device that works as an useful debugging too with and without connection to logic analyzer. I taped wire pieces next to each LED on the RS-232 Mini Tester to be instructions how to connect the adapter to logic analyzer (which wire carries which signal).
Take on any comms challenge by creating your own low-level protocol analyzer, high-level protocol analyzer, or measurement. And if you like, you can easily share your extension with the Saleae community.
Interestingly enough, we also use a named pipe in the application to get data from our analyzers into the terminal. We were considering looking at supporting multiple connections, so outside applications could use the same connection, but I think having an HLA do it us much more flexible, since named pipes are only one possible solution for streaming the data, and they are quite finicky to work with.
9 channels logic analyzer running at 200MSPS. 2Gb internal memory and USB streaming capability allows you to capture hours of logic signals, at maximum frequency on all 9 channels. Analyze dozens of serial protocols (like I2C, SPI, 1-Wire, RS232, CAN, etc...) using open source protocol analyzer library.
ScanaStudio is the software that runs all Ikalogic Logic Analyzer devices. It's super easy to use, yet, it's packed with professional features like protocol based trigger, packet-views or signal editor. ScanaStudio helps you get the most out of your logic analyzer.
SQ series (ScanaQuad) logic analyzer lets you capture, analyze and generate logic signals on 4 channels, at sampling rates up to 200MHz. They connect via USB to a computer running our free ScanaStudio software to display, decode and analyze captured signals.
SQ logic analyzer series is composed of 4 devices: SQ25, SQ50, SQ100 and SQ200. All devices have 4 channels, offer the possibility to capture and generate signals and work with logic signals in the range of 1.8V to 5V. The table below shows the main differences between the four models:
SQ series logic analyzers come with an embedded memory to store captured samples, as well as the patterns to be generated. Hence, SQ devices do not live-stream captured signals over USB. This has one big advantage: the performance do not depend on the host computer USB port performance
By combining logic analyzer and pattern generator capabilities in a single low price device, SQ is a perfect solution for students and small design houses. For more channels and more performances, check SP series logic analyzers.
I am using the TX1 and RX1 pins to communicate with a UART device but I am sending a bad command somewhere. So I am trying to debug using a logic analyzer(haven't used one in 25yrs). The only problem is I can't seem get the right data when connected to the transmit line. Does anyone know a good source for figuring out how to set the # of bits, parity and such...I've read a dozen or so wiki pages and understand that the it can be half or full duplex, 8 bit, no parity....it depends on the hardware. The device I have hooked up seems to work, but fails on one command and i just want to see what is actually being sent.
Generally 8 bits, no parity, 1 stop bit.Do you have a RS223 to USB adapter cable? You can connect your TX pin & ground to the RX pin and ground on the cable and monitor on a PC also, might be easier than a logic analyzer (since what you really want is a protocol analyzer). I have several of these laying around for some reason. I think mine have a Prolific chip in them.
Most logic analyzers cannot even see analog waveforms but Logic captures both simultaneously to analyze and display mixed signal waveforms associated with serial or parallel logic in the system under test.
There are alternative mixed signal options around such as the USB PicoScopes from Pico Technology or Bitscope but these are still adding some digital capability to what is really an analog USB oscilloscope rather than simply providing digital capability. One company making USB logic analyzers without analog is TechTools. They make USB logic analyzers with 9 to 36 channels with sample rates from 100Ms/s to 400Ms/s and up to 500Ms/s with half the channels used on the largest unit.
Even more useful to me is the ability to plot the data in analog form. In this case the SPI data is from a dual channel 16 bit analog to digital converter (ADC) and the facilities within the Digiview software allow you to decode the alternating data into two analog streams. I am not sure if this is a common feature of bus analyzers but it suggests that the people who wrote the DigiView software have designed it to be used in real applications.
One particularly interesting feature of the TechTools logic analyzers is the hardware compression used for storage of the data. This may be typical of modern logic analyzers and it minimizes the data storage used when nothing is happening. So, while the 1M words of storage would be full in a few milliseconds without compression on the 400Ms/s unit I have been using, I was able to make captures of several seconds due to the compression.
We have a task in hand to sniff a RS232 protocol in a certain industrial automation setting (we have been asked to do this legally by the manufacturing company itself). We are planning to send a technician for this task (as it is overseas) and provide him with a hardware/software serial port sniffer/analyzer so that he can send us back logs with timestamps and protocol definitions and inturn our software team can define the protocol looking at those logs.
The graphic above illustrates a typical RS-232 logic waveform (Data format: 1 Start bit, 8 Data bits, No Parity, 1 Stop bit). The data transmission starts with a Start bit, followed by the data bits (LSB sent first and MSB sent last), and ends with a "Stop" bit.
Designing / debugging a communication project can be very stressful and time-consuming. Many software / site engineers get stuck on the protocol before they can actually control a serial device, such as RS232, RS485, RS422, TTL, Modbus, PLC, or SCADA. Serial protocol can be very complicated; it requires that you not only understand the context of the protocol and the data format (ASCII, Hexadecimal, Binary, etc.), but you must also know how to do the Checksum calculation (the additional bytes added at the end of the data string to check the data integrity. Checksum Calculation varies from the simplest xOR to sophisticated CRC). Timing is also critical since some protocols require acknowledgment / response within milliseconds.
With the logic analyzer of the SQ series (ScanaQuad) you can acquire, analyze and generate logic signals on 4 channels with sampling rates of up to 200 MHz. They are connected via USB to a computer that runs the free ScanaStudio software to display, decode and analyze acquired signals.
With 4 channels, the device offers users with a small budget all the requirements that are needed for the analysis and debugging of serial protocols. The SQ series supports a variety of protocols such as SPI, I2C, USART, 1-wire, CAN, LIN, I2C, RS232, RS485, TWI and much more
To be complete: on almost all USB-based logic analyzers, protocol decoding is done in software. This means that data is captured over a defined timespan, transferred to PC, and this section is decoded in software. Even though you can search through decoded data, there is no robust way to trigger on it. This would require the decoded data to be available in hardware, and the logic analyzers which do support this typically cost a multiple of a full SmartScope.
As with an oscilloscope, a logic analyzer needs to have a reference of the 0V level on the device to measure. Therefore, you will need to make at least 1 connection between the ground of the SmartScope and the ground of the device you want to test. After that, connect the inputs of the SmartScope to the signals in your circuit of which you want to capture the data.
Today's integrated designs need an oscilloscope that is just as integrated - such as the MDO3000 Mixed Domain Oscilloscope (MDO) Series. It is the ultimate 6-in-1 integrated oscilloscope that includes an integrated spectrum analyzer, arbitrary function generator, logic analyzer, protocol analyzer, and digital voltmeter/counter. The MDO3000 is completely customizable and fully upgradeable. Add the instruments and performance you need now - or later.
Discovering a device fault is only the first step. Next, you must capture the event of interest to identify root cause. To enable this, the MDO3000 contains over 125 trigger combinations providing a complete set of triggers - including runt, logic, pulse width/glitch, setup and hold violation, serial packet, and parallel data - to help quickly locate your event of interest. And with up to a 10 M record length, you can capture many events of interest, even thousands of serial packets, in a single acquisition for further analysis while maintaining high resolution to zoom in on fine signal details. 2b1af7f3a8