VM110 Problem with connecting, disconnecting randomly, locki

I have a VM110 with 4 digital outputs (1-4) controlling (4) 12V relays switching 110V AC at extremely low amperage (about 0.06A). My problem is that when switching rapidly the VM110 will sometimes disconnect and reconnect or sometimes lock up all together (output 8 on solid until I un-plug and re-plug the USB cable).

I have the relays configured as designated on page 8 of the manual. I have tried this with and without the “clamp” pin connected but still have the same problems. I originally had the VM110 in the same electrical box with the relay board but have since moved it to a remote location to eliminate the possibility of magnetic interference from the AC voltage. This improved the situation some what but I still am having this trouble from time to time.

Do you think that the contacts on the relays could be arcing causing a power spike or something that shuts the board down as a safety precaution? The reason I think that is I have accidentally wired something to ground before and the board automatically shut down but reset itself after I corrected the problem and then unplugged and plugged the USB cable. What is the fastest rate the outputs on the VM110 are designed to switch?

I think the reason to the problem is, as you expected, the electrical interference and “noise” from the relay board.
You may try some sort of filtering between the VM110 and your relay board:

  • Add serial inductors or ferrite beads to both the digital output and to the GND wire.
  • Add parallel capacitors between the VM110 digital output and GND.

The maximum output speed is 10ms / instruction.

I am going to try ferrite beads first is I can find a source locally.

Can you clarify the parallel capactors?

Do you mean putting a capacitor between the ground line and each output? Do these need to be polarized? Am I correct in assuming this will act as a cushion for noise from the replay board?

Thanks for you help

I’m not sure if it helps but you may try.
Put 10nF ceramic capacitor from the digital output to GND.
The capacitors are needed only to those outputs that are connected to the relay card.

Add ferrite beads to all the wires going to the relay card.

It may be also good idea to add 10nF ceramic capacitors at the relay card inputs. Put those between the coil inputs and the GND of the relay card.