Hi Sergey, I am involved in the design, building and servicing of production machinery for thin-film solar cells. So I am on the side of a possible customer (we already have such test equipment, so I am NOT a potential buyer...).
I would never ever use such test equipment, if the outputs were NOT galvanically isolated. Not because I would be afraid of the machinery to test and calibrate, but because of the test equipment itself and the user! I cannot follow your argument, that galvanically isolated outputs should have lower precision: use a galvanically isolated data bus (I2C comes to mind) and a galvanically isolated DC/DC converter between the main part and the output module.... and there you go. Just to put you on a track: for example www.omega.com has calibrator and test equipment for both resistors, RTDs, 4-20mA and thermocouples. Uwe. > Hi everybody, > It is suggested to our company to make a design of some test equipment for > testing functionality of data acquisition systems for industrial automation > (from different suppliers). > The systems that must be tested can have, in particular: > 1) 4..20mA inputs; > 2) Inputs for RTD sensors, 3-wire and 4-wire. > So we must have in our test equipment 4..20mA outputs, and some circuits, > that > will simulate RTD. I hope, that we can solve both of these problems. > But we are not sure that in the case when our outputs are not galvanically > isolated from each other, we do not run into problems with some systems. > From the other side, galvanically isolated outputs will be more expensive > and will have less precision. It is much better to have isolated groups of > channels. > Can somebody help to solve this dilemma? > May be, it is impossible or very rear case, when the equipment for > industrial > automation will not work with single ended 4-20mA outputs or RTD's that > are connected with each other? I suspect, that it is true, but am not sure. > I urgently need the answer. > Please help. > With best regards, > Sergey Langvagen. -- Author: Uwe Zimmermann INET: [EMAIL PROTECTED] Fat City Hosting, San Diego, California -- http://www.fatcity.com --------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB CHIPDIR-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing).
