This is still a work in progress, but since I made a lot of headway in the last week, I just had to post some pictures and details. I am making a custom test fixture for some cable harnesses we build at work.
Scope of Project:
The proto board will be in the enclosure with the display mounted in the top of the enclosure. The 2x7 connector will be on the front side facing the operator so that the adapter cable with the spring pins is easy to get to. There will be a set of "keys" on a key ring that will correspond to each cable assembly part number. When powered up, a bootloader program from the onboard EEPROM runs and the display will prompt for a key to be inserted into the 2x2 connector on the side. Each key connects an EEPROM so that the programmer has a specific configuration program. With a key inserted, the display will show "ready to test Part Number XXXX with X thermistors", and the test loop begins. The test loop consists of the following steps:
1) Read on board thermistor value as reference .
2) Read thermistors on 2x7 connector per key.
3) Compare values using appropriate tolerance.
4) Light the 7 LEDs appropriately (green=pass, red=fail, off=NA)
5) Display results on screen (IE: "All Pass" or "CH2 Fail High")
6) When the harness is removed and all readings are infinite, display will show the ready message again.
7) If the key is removed at any point, the tester will exit the test loop by rebooting to the bootloader code prompting for a key..
Attached are pictures of the prototype unit and a graphical representation of one of thermistor cable configurations we build (this one is 7 thermistors with 2 interconnects)