Digital display plug-in

A readout device connected to a parent metering system contains a digital display for circumventing the non-linearity of analog meter movement in the parent system. The readout device displays both numerical and dimensional information in a clear, legible form with both probe and range scale factors accounted for in the display itself. A "probe" switch on the front panel of the module encodes the logarithm of the scale factor associated with the probe in use to a two's complement binary number, and the full scale range information from the "range" switch is encoded in the same manner. This information, along with function information from the "function" switch, is processed by a scale computation circuit which positions the decimal point and causes the units of measurement to be indicated accordingly.