Valves : starting/stopping flow

[dmdodd]

Okay, I have DAQFactory Lite.

I am limited on Channels, and so need to accomplish the following with a max of 1 or 2 channels.

(1) I have a raw 4-20mA signal coming from a steam mass flow meter. It fluctuates periodically, so we add a rolling average to it (averaging the last 10 array inputs every 2 seconds).

(2) There is a physical ball valve in our test rig that allows the steam to start entering our reactor (otherwise the steam continues flowing through a 'vent line'). Before the ball valve is opened I want the "into the reactor" channel to read zero (even though there is steam flow through the mass flow meter).

(3) When the ball valve is opened I want the operators to click on an image of the ball valve, which then tells the channel "Steam_Mass_INTO_reactor" to start logging the "Steam_FROM_Meter_Mass_Flow" value.

I've tried making the ball valve image linked to a V.channel, but the V.channel can't be used in sequences it doesn't seem.

I've tried sequences like:

while (V.FV_12 = 1)

Steam_Mass_INTO_reactor.AddValue(Steam_Mass_Flow_Avg)

endwhile

I'd love to be able to only use about 2 channels, so one (1) will be the 'rolling average steam mass flow' (converted from the "Mass_Flow_From_Meter" meter voltage input), and one (1) would be the "Steam_Mass_INTO_reactor". It'd be great if I didn't have to use additional channels for the valve "FV_12", or the initial raw voltage input channel "Steam_FROM_Meter_Mass_Flow".

Horrifically complicated and poor explanation from me I know, but see if you can shed some light.

Thanks,

Dan

[AzeoTech]

V channels can be accessed in sequences. The problem is you used "=" instead of "==". == is for comparison, = is for assignment.