The analog input modules use microprocessor-controlled, high resolution, 16-bit, sigma-delta A/D converters to acquire sensor signals such as voltage, current, thermocouple or RTD.The digital input/output channels provide three operational modes, with each channel able to set its operational mode independently. The counter/frequency module offers two 32-bit counter channels and a built-in programmable timer for frequency measurement. The relay module offers six isolated digital input channels and six isolated relay channels.