relay module work unstable

[markeev]

I have purchased some MICRO USB Control 5V 4-Channel Relay Module.
Sometimes it cannot ON or OFF the relay by click ON/OFF on RelayBoardManager.
Must close application and run again.
If connect to OMRON, will be more unstable.
How to solve? Thanks!

[con-f-use]

You will need to provide more details. There is a number of reasons this board might fail.

 - Cheap relays sometimes get stuck in one position (because some glue or sealant leaked or the contacts get fused together)
 - The USB communication might get out of sync and disconnect the board (from the price I assume it's using V-USB or similar which doesn't work perfectly)
 - There might be a bug in the software
 - Some channels might be overdriven and cause the micro to fail (too much current on a pin)
 - ...

When the failiure happens check whether...

 -... the PC still recognized the USB device
 -... shaking the relays gets the relays unstuck (BE VERY CAREFULL NOT TO TUCH THE LIVE CONTACTS!)
 -... wrong relay contacts are fused together
 -... the build in serial is able to toggle the relays
 -... the fuse or chips get gets hot
 -...

That's all I can think of on top of my head. Use your's now!

BTW: While at the topic of relay boards, does anyone know if there is a chip similar to the ULN2803 (multi-channel darlington driver with fly-back diode) that is also opto-isolated and not too expensive?

[TopLoser]

Are you switching inductive loads that are creating back-emf arcs that are crashing the micro on the board?

[Rick Law]

Check your power level on the board.  The relays requires quite a bit of power for the relay coil.

I use same model Songle relays (on a different style board).  Each relay requires 89.3mA (from data sheet, nornimal) to drive the coil.  Add to that, you need some power to drive the other components.  In real life measurement, it takes over 75mA to hold.  I have not measured the pull-in current requirement.

So, their 400mA specs has very little headroom.  If you have something else connected to the same USB port/hub, your board may not have the needed power to drive/hold the relays.

I can see there is a pin-header, check and see if it has V+ in.  If so, you can external power it and see if the problem goes away.