You can use two frequency-monitoring channels in the DAS to monitor the pulsed digital output from a tachometer. The channels can also serve as general-purpose frequency counters. The original intent of the five digital, input lines in the DAS was to monitor digital voltage-identification lines. You can use these lines as general-purpose input lines. Figure 1 shows a thermostatic sensor.
Easy expansion is also possible by selecting a different device address.
Using a different device-address bus needs no additional communication lines, because multiple devices may reside on the same bus.