SLC500 Processor / Controller 4-Channel T/C & mV Input Module - Thermocouple Types J, K, T, E, R, S, B, N, �50mV, �100mV and CJC. 1746-NT4 provides a choice of four filter frequencies, permitting you to select input noise filtering appropriate to the application and surrounding environment. Either or both 50 Hz and 60 Hz noise can be filtered from the input signal for greater noise rejection and resolution. The 250 Hz filter provides minimum noise rejection and is best suited for mV input applications where fast response to step changes is required.