I have a device that is outputting the signal seen in the attached files. This signal comes from a two conductor 1/8" phono jack, and is normally sent to another device which controls a stepper motor. This signal is a number of pulses directly representing the number of steps for the motor to move. My goal is to bypass this device and produce this signal programmatically from a computer. Ideally there would be a small device external to the computer, connected to it via USB. The device would probably appear as a com port. It would have four to eight 2 conductor 1/8" phono jacks and I could simply send a number representing the port, and the number of pulses to the device from my program, and the pulses would be sent. I don't know what sort of signal this is. Is it AC current with the signal superimposed ? It all looks the same with the scope in AC or DC mode. I don't know if the 60 Hz background signal is because it is AC, or if it is hum leaking in. I read the pulses as being 1 millisecond apart. I have no idea how I could create such a signal unless I could do it as an audio signal. Theoretically I could record this signal as audio. I could record 100 versions, one for each possible number, and then selectively play them to produce the signal. But I don't have any idea if this is anything like an audio signal, or if audio would reproduce it. Perhaps there is an existing device that does what I need.