how to operate a solenoid valve depending on temperature input

[vishnu_reddy]

Hello Everyone,

I need assistance in developing a labview program to operate a solenoid valve (parker's series'99). I have some NI modules NI 9213 (to read temperature at the surface of the copper plate using thermocouples), NI 9401, NI 9474. I would like to operate a solenoid valve depending on the surface temperature of that copper plate. the copper plate is heated using a resistor attached to it from the other side. suppose if i want to maintain the surface temperature at 35 degrees celsius. the solenoid valve has to switch on ( starts operating) if the temperature raises above 35.5. so that the valve allows liquid to wet the copper plate thus maintaining the copper surface temperature at 35 degrees. apart from this the valve frequency and duty cycle should be maintained manually. 

your suggessions will be of great help to me.

Regards.

[SteveD123]

Why not just use a thermostat? e.g. http://uk.rs-online.com/web/p/thermostats/7334723/ ? I have not checked this will operate a Series 99 though. But it looks although this is a classic heat/cool PID temperature control application. The cooling power needs to be part of your PID setup, typically as negative power output. Or you could use a full-blown temperature controller, e.g. something from Eurotherm.

See this post for general advice about driving solenoids from digital I/Os: http://forums.ni.com/t5/Digital-I-O/power-excitation-for-solenoid-valves/m-p/3225806#M20573

[Gregory]

You can do something like this. It is a VI Snippet so you can drag it onto your block diagram and it will become code.

[vishnu_reddy]

thank you steve & greg

[GerdW]

Hi gregoryj,

why do you need so many case structures? (Especially those that output a TRUE/FALSE when case selector is TRUE/FALSE, respectively!)

[Gregory]

Hi Gerd,

Because he's planning to send some commands to something.