How can I tell if my HI 2151/20WC needs a new SMM?

If your HI 2151/20WC is having problems retaining its calibration after a power cycle then you will need to upgrade your unit. Please see notice below:

NOTICE: The HI 2151/20WC was discontinued in 2001 when many components became obsolete, including the Secure Memory Module (SMM). The HI 2151/20WC SMM incorporates the use of a built in battery to store memory during power loss, and the shelf life is 7 years. Once your SMM battery dies and you experience a power loss, you will lose your configuration data and we do not have a replacement available. We highly recommended you replace your HI 2151/20WC with a current model Hardy Instrument before that happens. Please contact your Local Hardy Rep to review your application requirements and determine which current model Hardy Instrument is right for you.

If your HI 2151/20WC unit has 0650-0035 or 0650-0056 firmware, then it uses a different SMM and has a battery back-up on the board. If this version of the unit looses calibration with a power cycle, then it is a battery problem rather than the SMM.