Wow, what a responce, thank you all for your input! To make it a bit clear how "fast" the readings should be I will explain some bits. Our engine is a diesel but we "homebrew" some electronics so we can control common rail injectors instead of ordinairy mechanical ones. The injectors uses 80v. 35a. to "unlock" and 12v. 12a. for the real spraying so there will be some interference so shielding has to be done. The engine is build for full power only, so on the startline it will be throthled up to 6000rpm and 80% (5bar) turbo pressure (wich can take up to 30 seconds) before the clutch will be released and in the following 6 seconds full throthle will be given and "hell brakes loose". :-) (b.t.w. in a diesel puller the engine is "overfed" with diesel so it's very very rich so using a lambda probe isn't really usefull, the reason for this is that thick black smoke is a lot "heavyer" than normal exhaust fumes therefore containing more energy so we can use a bigger (read oversized) turbo wheel, example: http://www.japie.deserver.nl/ftp/Hans_Boxler.wmv)
Data logging has 2 objectives, first is to find out why and where something went terrebly wrong, second goal is to show us why the engine was running so much bether one match than the other. For the "something went terrebly wrong" part we need accurate and fast timings. temp. readings and humidity are for engine adjustements so 500ms. will do, pressure readings for turbo boost and oil can contain info about a engine crash so 100ms. at least. As for rpm readings it's problematic, if the engine is running 10.000rpm the camshaft is doing 5000 so the "slowest" pulse I can get of it is 90 times per second, but I would like to know both the speed of the crankshaft as the camshaft because after a blow-up it would be nice to now if the engine was damaged because the cambelt broke or that the cambelt broke because of the damage... In the project I want to read the owfs with rrdtool and writing the rrd-db to an usb-stick. This stick can be copied after a run for later use. I'am planning on using the ASUS WL-HDD2.5 with openwrt/owfs/rrdtool, only donwfall is that it has only one usb port so a hub is needed. (on the other hand thats positive since I have all the hubs ports for 1wire so I can use a single one for the fast timings of the crankshaft one for the camshaft and another for temp. and pressure readings.) On openwrt I like to place a webpage with rrd-images of the run so we can read-out the values via wlan right after a run (or crash). As for the sensors, DS2423 sounds great using a sample rate of 50ms. I could use both crank and cam on one wire. Are there any shematics around on how to hook it up to an magnetical or optical pulse signal? The DS2450 should be great for temp and pressure, every automotive sensor gives 0-12v. so I could make a smal device converting 0-12 to 0-5 wich can be used for every sensor. As for humidity is there something usable available for that (since it's placed inside the inlet channel wich is under 7bar pressure) or should that be homebrew also? And does anyone of you guys know some great documentation on how to hookup and setup a 1wire system? (owfs itself is well documented as is openwrt) -- Groetjes Japie ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys - and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV _______________________________________________ Owfs-developers mailing list Owfs-developers@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/owfs-developers
