fieldpoint write

[Fishy]

I am reading dissolved oxygen data from a cfp 2120 through AI 100 analog modules, no problem.  Trying to control a closed solenoid oxygen valve through a fieldpoint read/write vi using a DO 400 module using channel 0. My objective is to deploy the project realtime, but for now we are just testing the system from the development PC.   VI reads O2 level and compares to minimum less than or equal to comparison in a FOR LOOP.  Vi works fine.  However, neither MAX nor the remote cfp 2120 detect a write to channel 0 of the DO 400.  In MAX I can manually write to the channel successfully.   cfp 2120 and Development PC are on the same subnet and all other communication appears successful.  Any suggestions? Thanks.

[RavensFan]

Check to make sure you have the latest fieldpoint drivers.  Check that you have the DO module configured in MAX.

Do the appropriate LEDs such as Power and Ready light up at the top of the module? 

What are the specifications like voltage and current draw for this solenoid?

How do you have the solenoid wired up?

Do you have the power supply connected to the V and C terminals of the connector block?

Do you have any voltage suppressor or flyback diode installed across the coil of the solenoid?

What exactly do you mean by the remote cfp 2120 doesn't "detect a write"?  Does that mean it doesn't actually write, or that it does but neither MAX nor LabVIEW sees that the write actually occurred?

Does MAX or LabVIEW provide any error codes when they attempt the write?

[Fishy]

Thanks for the reply. 

Check to make sure you have the latest fieldpoint drivers. Did this...upgraded to fieldpoint 6.0.4.

 Check that you have the DO module configured in MAX.  It is configured in MAX.  I can right click a channel and write a 1 or 0 to it successfully.

Do the appropriate LEDs such as Power and Ready light up at the top of the module? Yes

What are the specifications like voltage and current draw for this solenoid?  24 v, 0.5 amps

How do you have the solenoid wired up?

Do you have the power supply connected to the V and C terminals of the connector block? Yes.

Do you have any voltage suppressor or flyback diode installed across the coil of the solenoid? No

What exactly do you mean by the remote cfp 2120 doesn't "detect a write"? I  had the VI write to the LED's on the cfp2120 instead of the DO 400. They did not light up;  However, if I manually write to the LED's in MAX, they light up. 

 Does that mean it doesn't actually write, or that it does but neither MAX nor LabVIEW sees that the write actually occurred? correct

Does MAX or LabVIEW provide any error codes when they attempt the write?No.  The VI appears to be running normally, there is just no acknowledgement of a write in MAX "value column"  ie, no change.  I also have a volt meter wired to the connector block and when operable, you can hear the solenoid click open or shut.  There seems to be a disconnect from Labview to MAX.  All read functions are normal, data logging using a variety of methods works fine, etc.  It is just this write.  Wouldnt I see a value change in the value column in MAX?  Thanks for your help...

[RavensFan]

It sounds like you have one or two problems here.

1.  Your FP write is not working in LabVIEW.

2.  You aren't seeing the write in MAX even though the solenoid is working.

#2.  In order to see the change in value in Max, you have to hit the Start button at the top of the screen in MAX.

#1.  I don't know why you wouldn't be able to write to the  LED's on the controller if you are able to write to the channels on the DO400.  I would check the way those LED's are being addressed in LabVIEW.

I would highly recommend putting a diode across the solenoid coil.  A danger with an inductive load such as a coil is that when you break the  connection, there will be a voltage and current spike that could damage the digital output channel.  The diode will prevent that.

[Fishy]

Thanks Ravens Fan.  Yesterday outstanding support from one of NI's great young engineers worked through the problem.  Dont really know what happened, but re-formatting the cfp 2120 and reinstalling drivers has apparently solved the problem.  There were some minor changes to the vi.    However, will take your advice about the diode.  Thanks so much for your assistance.  Fishy.