... <2 KHz. 3, Allowable working voltage: DC5V, 12V,24V. 4, Far Distance: 1 km (metal wire resistance ≤ 390 ω) 5, The ambient temperature ... non-contact, sending letters and reliable.3, the long transmission distance, square wave output.4, explosion-proof and intrinsically safe Flameproof ... 2 KHz. 3,Allowable working voltage: DC5V, 12V, 24V.4,Far Distance: 1 km (metal wire resistance ≤ 390 ω)5,The ambient ...