Multiplexers in Analog I/O Modules


Thread Starter

Lito Torres

I need to know how Multiplexers works in an analog I/O Modules. Also, please help me find an article on how analog signals are programmed in a PLC. Thanks.

Byte Mechanic

The multiplexer works like a row of field-effect transistors where only one is on. The OFF FETs have high resistance and isolate their inputs from the output. The ON FET has a low resistance and it's input is effective at the output. Programming is just a matter of selecting the correct input. All inputs are reference to the device ground and must be within the chip's limits. A common limit is 0 to +5 volts, and 0 to 5 milliamps. Addressing is chip specific, so read the manual.