The main cause of losing communication is a poor serial port on the PC.  Historically poor serial ports are more common to older named make PC's.

If at all possible, try the instrument on another PC, preferably a different make and a fairly new model.

If it does appear to be the PC's serial port, then solutions are to either install a quality PCI serial card or a USB to serial converter.  Not all USB to serial adaptors work, please see the USB connectivity section. For advice please contact ACM Instruments direct.

If the instrument is a field/battery operated instrument, then it could be caused by the battery (see the battery care section).

Another possible causes could be a poor mains supply.  Avoid using UPS, they sometimes produce a crude square wave.  Avoid powering the PC and instrument from the same mains supply as high power equipment, such as pumps and heaters, in these situations try running an extension lead from a near by office which may be on a different mains ring.

If the cause still can't be found, don't panic, contact ACM Instruments for advice.