Designing Reusable Testers - Page 1
Forum section: electronics / projects

author: Robert.Adams
author_rank: Contributor
timestamp: August 07, 2017, 01:23:12 pm
content: Hello everyone,I've been working (day-job, so actual details are going to be sparse here) on a load-board for 'exercising' and functional testing a design. The exercise mode is intended to be as dumb as possible, with just resistive loads for outputs, and a few states for analog/digital inputs. Functional testing has more features, such as measuring voltages and currents, toggling every input, etc.This amount of work gets crazy for modules with 100+ connector pins so I've been hunting for a more modular/re-usable test design. Does anyone have any suggestions? It needs to still be portable since we bring these to external test houses - no humongous NI Labview setups.Regards,Bob

author: Rerouter
author_rank: Super Contributor
timestamp: August 07, 2017, 10:30:32 pm
content: For decent answers, try being sparse on what the thing your testing is instead of how you need to testWhat kinds of peripherals are you testing, is it high side switches, low side switches (for the resistive stuff), ok if so what resistance or current ranges do you need to cater for, and for how long.If its digital IO, what data and edge rates do you need to cater for, is it just a repeating sequence, or does it need to be generated live?Are the tests sequencial, or all at once.How many unique analog measurements do you need to cater for and to what resolution, e.g. could a window comparitor with a dual dac get you by.Etc.This leaves us with no idea what you magical black box is, but would give the amount of detail required to assist yoy.

author: joeqsmith
author_rank: Super Contributor
timestamp: August 08, 2017, 03:52:55 am
content: Based on your signature, I am assuming your job is testing various automotive modules, ECM, brake controllers and such.LabVIEW in itself is not physically large. I assume to run this setup with a PC to collect the data. IMO, this is really where LabVIEW shines.These are some videos I made a few years ago showing a small HIL simulator I developed for a 4 cylinder engine. I designed this system for the fun of it. There is nothing proprietary, so feel free to ask any questions you may have.This first video is showing the HIL simulator along with a low cost data acquisition system that I am using with using LabVIEW.This video shows the box that contains all the loads and drivers to interface with the ECM. The knobs and switches on the front are for a manual control but for the most part I just use the computer to automate everything. There is a custom board that sits inside the PC that handles all of the timing and such.This video shows some free tools I was looking at to attempt to speed up the model. Since then, I bought a new PC which his more than enough computing power to pull everything off in LabVIEW including the interrupt service routine.

author: Robert.Adams
author_rank: Contributor
timestamp: August 08, 2017, 03:10:58 pm
content: Quote from: Rerouter on August 07, 2017, 10:30:32 pmA mix-match of high sides, low sides, H-bridges. Some drive inductive loads in the application, but I can do basic testing with resistive loads. Currents can range from a 1mA digital output to a 10A H-bridge.Quote from: Rerouter on August 07, 2017, 10:30:32 pmDigital IO is mostly dumb switches that toggle every few seconds in a test profile. There can be up to 4x LIN or CAN bus (typically 500kbps, but can be higher). Typically <5 digital pins or so of 100Hz or lower input frequency. Depending on the test, the communication busses are converted to USB and simulated/read by a test laptop.Quote from: Rerouter on August 07, 2017, 10:30:32 pmFunctional test is sequential, but exercising is a mix of outputs on in parallel to simulate a controller's operation in vehicle. This means it probably toggles from custom states based on test software in the module.Quote from: Rerouter on August 07, 2017, 10:30:32 pmUp to 50 analog inputs in a mix of 10 or 12-bit measurement on module. Tester doesn't need to measure them this well. The current thought is to multiplex a matrix of relay's to switch a DMM to each channel so the tester can verify the voltage on pin for every channel sequentially in functional test. Not required to verify the pin voltage in exercise mode.The real struggle is to design a functional test setup that is both portable and modular. I'm thinking the solution would be some sort of rack that is smaller than a 19" server rack, since testing will involve carrying at least 1x functional test setup and 3-4 exerciser setups for tests that benefit from running multiple modules in parallel. If we had some sort of rack functional tester we might be able to design jumper harnesses and swap out loads on cards to accommodate multiple projects.

author: aiq25
author_rank: Regular Contributor
timestamp: August 08, 2017, 05:40:10 pm
content: Should be an interesting project. I also work in the automotive industry and have worked on designing ECU testers (80+ pins modules) and have designed a tester for sensors (hardware/software).What kind of solution are you looking for? Are you looking for a custom solution or something off the shelve? I'm assuming your testing one module at a time? Or are you looking for something that can test multiple modules at once? How portable does the solution have to be?I think I have an idea of what your looking for. For the testers we worked on it was custom hardware paired with NI TestStand. For the best solution your probably going to need to create custom hardware/software, it can be quite time consuming but will give you the most portable tester.The max current I have worked on with the testers was 2A and designs get a little tricky when dealing with this kind of current.