Compact RS232 port sniffer that is auto configuring and has ASCII display  ? - Page 1
Forum section: electronics / testgear

author: Fraser
author_rank: Super Contributor
timestamp: July 14, 2015, 11:42:08 am
content: I have been looking for a simple serial port sniffer of recent, but have not found what I am looking for.Does anyone know of a two wire RS232 sniffer that can be quickly connected to a DUT serial line and that will auto recognise baud rate etc and quickly show what ASCII data is passing over the RS232 unidirectionally ?A scenario...... I have dedicated computers buried inside equipment that often have RS232 engineering ports on the PCB. I am looking for the simplicity of a logic probe that auto configures itself like many simple DSO's and displays what the SBC is saying at boot.Presently I have to use a DSO to discover the baud rate, parity, data bits, stop bits etc before telling my logic analyzer what it is looking at. Alternatively I just set the common start, stop data and parity values and step through the baud rates. An LA also needs my PC to be be present and that makes the quick monitoring of a port a more time consuming and bulky process.Having seen devices like the Bus Pirate and protocol analyzers I hoped that someone had designed something that could do the above and display the text on a built in screen with page up and down capability. Sadly I am not a coder so such programming is currently beyond me.If anyone knows of such a device on the hobby market, I would love to hear about itAurora

author: Wilksey
author_rank: Super Contributor
timestamp: July 14, 2015, 11:51:23 am
content: I don't know of any, I built one ages ago, I used a PIC, a few RS232 transceiver chips, I had the monitor plug in between the two devices, and used A usb -> serial converter to interface to another UART on the PIC which formatted TX and RX data.

author: Whales
author_rank: Super Contributor
timestamp: July 14, 2015, 12:15:26 pm
content: It looks like you want a solution that attacks this problem from below: a simple microcontroller device with a screen and some firmware. It's probably better to attack it from above: a cheap laptop with a USB <-> rs232 dongle and some term software with automatic parity/stop/etc detection.

author: frenky
author_rank: Unknown
timestamp: July 14, 2015, 12:40:29 pm
content: I own one of these Asus eee 701:http://goo.gl/j1IzmSI use it ony for configuring my VDSL modem which I have in the attic.For that price you probably can't get better hardware serial port monitor.These one are even better with 9" screen:http://www.ebay.co.uk/itm/ASUS-Eee-PC-901-8-9-Laptop-Netbook-Win-XP-/321800839622?pt=LH_DefaultDomain_3&hash=item4aecd321c6http://www.ebay.co.uk/itm/Asus-Eee-Pc-901-Bk006-/121703171249?pt=LH_DefaultDomain_3&hash=item1c561304b1

author: Fraser
author_rank: Super Contributor
timestamp: July 14, 2015, 12:45:51 pm
content: Thanks guysI just thought I would check that I had not missed something dedicated to the role.Your recommendations are the likely reason that no one has designed such a 'probe'. I have plenty of laptops and netbooks sitting around doing nothing so will go the software RS232 sniffer route.CheersAurora

author: G0HZU
author_rank: Super Contributor
timestamp: July 14, 2015, 08:08:55 pm
content: Many years ago I made a serial port sniffer using a cheap HP IPAQ H2210 'Pocket PC' PDA that had its own RS232 serial port. It could also send RS-232 as required.I used Embedded VB to write the app on a PC and this gets transferred to the PDA as an executable application. The nice thing about this approach is you get a pocket sized sniffer/sender that can also post process the info it sniffs and you can easily add things like guages or bargraphs on its little colour LCD display or log data to memory inside the PDA to dump to a PC at a later time.I'd imagine you can buy these old PDAs for peanuts on ebay and the developer tools for writing the apps were all free and Embedded VB is very similar to the old school VB6 for Windows.

author: artag
author_rank: Super Contributor
timestamp: July 14, 2015, 08:56:50 pm
content: I used to use an HP4951C for this. It's getting a bit long in the tooth now (can't handle high baud rates) but it does a good job. I think there was a PC-based tool (CAT or something ??) but it used a plug-in card - PCs didn't often have multiple serial ports, weren't fast enough etc.It's easy to get multiple serial ports with USB, but I suspect they're really poor at auto-bauding. You really want some dedicated hardware (even if it's just a pin on a micro to measure the bit times).Then you have the problem of display - the HP4951 was moderately good but still had too small a screen. The ones with dot-matrix LCDs were dreadful. PC was better .. if you don't mind carrying it.A really nice solution might be made with a tablet, a Saleae-style logic analyser, and Sigrok.

author: Fraser
author_rank: Super Contributor
timestamp: July 14, 2015, 09:07:42 pm
content: I have dug out my little Datawind Ubisurfer that is running XP and has a very fast boot thanks to its Solid State driveI bought it new for only £15 a couple of years ago with the thought that its fast boot and small size might prove useful. I was right for onceThese were sold off cheaply when better Netbooks came onto the market. The Ubisurfer is capable of running PC software so is more useful than the later Android types of netbook.The Ubisurfer is is equipped with three USB ports and Wi-Fi so connectivity should not be a challenge.I shall load up Portmon and see how well it workshttps://technet.microsoft.com/en-us/library/bb896644.aspxUPDATE: Damn, I was wrong. The Ubisurfer runs Win CE 6.0I do own an HP H2210 PPC but I got fed up with it forgetting all its programs every time the battery went flat so that is sitting in a cupboard somewhere.I'll use one of my Sony Vaio Netbooks instead.Aurora

author: Fraser
author_rank: Super Contributor
timestamp: August 06, 2015, 05:13:21 pm
content: As an ending to this little odyssey I thought I would advise readers of my recent purchase that solves this problem for me.Whilst searching for data analysers I stumbled upon a unit for sale on e*ay that dates back to 1987Some might dismiss it immediately due to its age but the 1980's were the era of RS232 communications so this is a good hunting ground for RS232 analyzers. The problem is finding one that still works and is in good condition.I found the Wandell & Golterman DA-15 and did some research on it. It is poorly documented on the internet because of its age but I did establish that is is a data analyzer designed for investigation and diagnostics on analogue and digital data paths. It is a V.24 RS232 analyser that also supports other data modes, like X.25, using option modules. Thankfully my unit has the user manual included.As supplied it has the following major features:1. DLM : V.24 RS232 Data Line Monitor - DCE, DTE or both using the supplied 'Y' monitoring cable.2. BERT : V.24 RS232 Bit Error Rate Tester for sending data around a data loop looking for performance issues and errors.3. Async Term : Asynchronouse V.24 RS232 terminal TX & RX data4. Lead Stat : Lead state on teh V.24 RS232 port - Like a BoB that shows what is happening on the various pins of the 25 pin port.5. DVOM : Digital Volt Ohms Meter - DCV, ACV, dBm, Ohms, Continuity with selectable threshold.6. Spkr Mon : Variable gain audio amplifier and speaker for audio monitoring of input (BNC or RJ11 input).The inputs to the unit are a V.24 RS232 25 pin port, A BNC (for DVOM) and an RJ11 (for DVOM)Outputs take the form of the backlit mono LCD panel, speaker (audio & alarms), and a parallel printer port.The unit can print out test results and logged data via the parallel printer port. An on board non volatile memory holds the logged data until the user requests a print out.The DA-15 is self sufficient using the built in rechargeable batteries.Cables provided with the DA-15 comprise: Mains Charger, Centronics printer cable, V.24 RS232 'Y' cable, BNC test cable and RJ11 test cable.Having read the provided thick manual it becomes clear that this unit was an expensive piece of test equipment. It has many user selectable options and all operations are run as 'programs' that may be altered to meet the users needs via the selectable options within the functions on screen description. At first look this seemed an odd way to select menu options but it does work well. Each function has a short description of what the unit will be doing. Within the text there are highlighted options that are changed by selecting them with the up down arrows and the F keys.Having used the unit for 30 minutes or so today, I found it very simple to use and very convenient. It provides a simple way to view data activity on an RS232 port with the added bonus of a V.24 terminal and DVOMA sort of super break out boxThe history of my unit.......My unit is brand new in the box and is Ex MoD stores stock. It has been checked for serviceability over the years and the battery appears to be working fine (which was a surprise !). I will check the main and data memory Lithium battery to see if they need to be replaced.This unit may be old but it is beautifully built and designed to be a useful diagnostic tool for working on RS232 data ports and links. Perfect for the work I do on embedded computers that have Serial engineering ports. Being new, it is in perfect operating order and I consider good value for £50.Whilst it would be true to say that a laptop can do much of the DA-15 units operations but this dedicated piece of test equipment is very efficient and compact at 8" x 5" x 3". It has the advantage of a fully populated 25 pin V.24 data port unlike many USB-RS232 adapters. It is also instant booting so no waiting for a PC boot sequence etc.I already have some nice level converters that can sit between the DA-15 and any 3.3V or TTL RS232 ports.Pictures attached

author: Fraser
author_rank: Super Contributor
timestamp: August 06, 2015, 05:13:57 pm
content: More pictures of menus etc.

author: retrolefty
author_rank: Super Contributor
timestamp: August 06, 2015, 05:59:24 pm
content: Reminds me of a 'Datahawk' unit we bought in the refinery around 1979. We were starting to connect some many different manufactures equipment to our equipment and start-up communications testing was always a painful and time consuming task. Everyone seemed to have their own interpratation of the RS-232C standard or sometimes even ignored or violated the standard. After obtaining this unit we could solve problems in at least a tenth of the time. The unit could act as either a sender, receiver, or monitor both sides of a full-duplex channel. Cost like $8,000 at the time but paid for itself very quickly. Here is a picture image I found via goggle.http://www.ebay.co.uk/itm/VINTAGE-INTERNATIONAL-DATA-HAWK-4010-DATATRAP-COMPUTER-/320948132489

author: Fraser
author_rank: Super Contributor
timestamp: August 06, 2015, 07:10:47 pm
content: I forgot to mention, I also bought a neat little 4 channel unit from IKA called the Scanalogic-2 PLUS. I bought the EDU version which is a DIY build as the built unit was just discontinued. For the asking price of 33 Euros it looked useful to have on the bench for serial data work. It can decode RS232 , I2C data and other serial standards.http://www.ikalogic.com/ikalogic-products/scanalogic-2/http://www.ikalogic.com/scanakit/I do have the Zeroplus LAP-16128 Logic Cube and Hantek 4032L 32 channel logic analysers but something about the IKA offering appealedAurora

author: G0HZU
author_rank: Super Contributor
timestamp: August 07, 2015, 10:05:03 pm
content: QuoteYes that can be a major pain with the H2210 but I use the backup/restore feature on mine to ghost an image to a PC. It only takes a few minutes to restore all the data after a recharge and this is only a fraction of the time it takes to recharge the battery.But it is still very annoying that they made it 'volatile' like this...But it really is a neat little debug tool. I used to use it on the dash in my car to datalog my car's ECU and show a realtime display of all the engine (and driver inputs and outputs from the ECU including speed and MPG economy) This was all done by converting the sniffed RS-232 data from the ECU into graphics and text data for all these things.Or it could just be used as a simple pocket sized ASCII or Hex sender and receiver over RS-232.