I have spent some time researching the best USB converter to use with our instrumentation. USB converters using the FTDI chip set were by far the most reliable and we now supply these with our instruments.
If you are using a USB converter with the FDTI chipset, or any ACM Instrument with built-in USB, please download the drivers from here. This file also contains detailed instructions.
If you are using the version 5 sequencer software then details are available in the Total Tester help pages (Start Menu -> All Programs -> ACM Instruments version 5 -> Total Tester, Click the 'First aid' button). These help pages are also available on-line here.
For additional help with USB or Serial communication problems see Communication problem and Windows Vista, 7 and 8 USB Drivers which also includes video demonstrations on how to update your USB drivers and how to reset your USB drivers and a USB Reset Tool program.
Please contact ACM Instruments if you need further assistance.