TTL 0-5v Output Never Hits 0v



I have a cheap Chinese VFD setup and is working close to 100%, the only issue i am having is the 0-5V TTL outputs to control the VFD never actually reach 0v it always has a reading of around 0.125v even when the spindle is set to 0rpm and set off using g code.

I have measured the out puts with a multi meter and it never reaches 0v anyone know why?


does the masso output read 0v with out the VFD connected?

if so cheap Chinese would be the answer

you can put a 10k resistor between output and ground to pull down to 0v


MASSO Support
Staff member
Generally there is always some small voltage on the 0-10v output, please remember this is the RPM reference signal and you will need to wire the M3 output from the MASSO to your VFD's FWD terminal, this way when you give M3 command then this output will switch on the VFD ON and M5 will switch of the VFD OFF even if there is 10v on the 0-10v output.

In VFD control FWD or REV signals must be connected to MASSO for proper operation.