Solenoid causing LabVIEW crash?

[eichlerjw]

Hi

I am using LabVIEW 8.6 with an NI-9481, 4 channel relay module (amongst others) to control a solenoid valve which opens and closes a hydraulic circuit. The relay module controls a 24V DC supply to the solenoid.

The solenoid valve is opened and the hydraulic circuit operates. Once a condition is reached, the solenoid valve is closed by LabVIEW,shutting down the hydraulics. A few seconds later, the computer restarts.  To try to remedy this problem a diode was fitted, parallel to the solenoid to protect the circuit from back EMF's generated by the collapsing magnetic field in the solenoid.  This reduced the problem but has not solved it.

Can anyone suggest any remedies? Could the back EMF pulse be the reason for the computer resetting itself? Or could there be another reason?

Any help would be greatly appreciated.

Many thanks.

John

[Wayne.C · Accepted solution]

John,

I would think that the back EMF would be the primary suspect.  Make sure the the diode snubber you installed is as close the relay coil as possible.  This will maximize its effect. 

The next issue to look at is how the 24V power to the valve is wired with respect to the rest of your DAQ hardware.  Primarily worried about ground loops and ground bounce.  Can you describe the rest of the setup and how things are wired in a bit more detail?  Any other inductive loads in the setup?

[eichlerjw]

OK, The diode could be moved closer to the solenoid (i.e. across it's terminals). It is currently about 6 inches away. I shall do this tomorrow. The 24V supply to the solenoid is grounded and is in a separate, grounded enclosure which is adjacent to the DAQ module rack.

The rest of the DAQ system is comprised of 2 LVDT's (connected to one input modulue) and an accelerometer (connected to another module).  There are no other loads on the system as the solenod control is the only output.

I'll report back tomorrow when i have tested the system with the diode in the new location.

thanks for your help!

J

[RavensFan]

Could you be having a "blue screen of death"?  Just this morning I had to solve a problem with the PC restarting itself.  The error messages when Windows restarted told me nothing.  I found a tip on the forum how to turn on the blue screen message.  Go to My Computer/Properties/Advanced/Startup and Recovery Settings, and uncheck the box that tells the PC to restart itself.  Once I did that, I saw I had a blue screen related to the serial driver for a USB/Serial port converter.  That led me down the path to updating the driver and all seems to be working fine for the moment.  Now why the blue screen what able to know which driver caused the problem, but Windows didn't know when it restarted, that just shows the idiocy of windows.

If you have a blue screen, this will show it and maybe give a clue as to whether you have a crash due to a driver issue or some power failure.

[eichlerjw]

Hi.

Just an update to the situation.  After inspecting the diode it was found to have a poor connection.  After repairing this, the computer no longer crashes. Many thanks for all your help

cheers

John