Using a Function Generator Always Reads 0-5V Square Wave

Updated Jan 11, 2023

Issue Details

I'm using a function generator to generate a signal which I'm reading on my data acquisition board. However, the signal always looks like a 5V square wave. What's going on?


Many function generators have two outputs: a normal output and a TTL output. The TTL output will produce a 5V square wave with a frequency equivalent to the value that you programmed into the function generator.

For example, if you programmed the function generator to produce a 100 Hz, 2V peak-to-peak sine wave, the "normal" output will generate the intended sine wave; the TTL output will generate a 100 Hz, 5V peak-to-peak square wave. 

So, if you are always reading a 5V square wave on you DAQ board when using a function generator, make sure that you are not using the TTL output of the function generator.