Flow Meter

[maddave]

Sorry don’t know much about electronics …but what I need to do is for my computer to count the pulses from a flow meter and when the count gets to a set number send a signal to a relay ……. Can any one tell me if this can be done…and it so how...... please please.. tell me as if I know nothing about electronics .. thanks for your time

 

[Reloadron]

Can it be done? Yes, it can be done. The problem is how you want to interface the computer to the flowmeter (hardware) and how you want to convert the data from the flow meter to engineering units like GPM or whatever (Software). What exactly are you looking to do? What exactly do you have for a flowmeter? How would you like to interface to the computer, as in like USB port or whatever? Doing this can be simple to complex depending on how you want to go about it.

<EDIT> If this is an older computer or computer with a RS232 Serial Port and you just want a pulse count and then trigger a relay and reset it can be done relatively simple. All depends on the signal you have to work from. </EDIT>

Ron

 

[alec_t]

It can be done, but we will need to know the voltage and approximate frequency range of the pulses, also the type of relay.

 

[maddave]

Self service bar out side ….. the way it would work is : I have a bar outside all setup ready for service ….. the customer comes in to the pub with is pals he pays for 8 pints of lager he is then given a key that he can turn the lager flow on to one of the pump and when he is not using the pump he can turn it off to prevent anyone else using “his” pump ( all the equipment to do this I have that’s no problem) but when the pump as dispensed 8 pints I need it to send a signal to a relay that will shut a valve so no more lager can be dispensed until a member of staff resets the counter …

 

[Reloadron]

OK, so you would have X number of pulses per pint. The pulses compliments of the flow meter. Each pulse sequentially up counts and when the count reaches a preset the system shuts down for example the solenoid valve to the lager supply. Then the stystem can be reset to zero.

What still needs to be known are the flow meter data, things like pulse amplitude and number of pulses to the pint or whatever unit of measure you want. Meaning for example they are 5 volt or 12 volt pulses and there are 25 pulses (or whatever) to the pint of lager.

Doing a single station is easy. The running tally can be looked at in software.

Multiple stations would require multiple flow meters and each flow meter would feed another hardware device that would talk to a computer. I'll assume a Windows based operating system?

What you want to do is not all that difficult. Just a matter of hardware needed and softwware to read from the hardware. The starting point remains the flowmeter and the software would comprise what is called a totalizer showing a running total till the preset pints are reached and the system shuts down. So what is the flowmeter you have planned? Make, model and data?

Ron

 

[maddave]

i am willing to use any flow meter ... the one i have seen :

Flow Meter DBS 026



Suitablity Beer,wine,soft drinks,spirits and water



Operating Voltages 5 volt DC + or – 1 volt

12 volt DC + or – 2 volts



Typical Current Drain 5 volt version 10 mA,(12 volt version 15 mA available on request)



Signal Square wave,min 90% of supply voltage


Flow Rate Region of 1 litre to 25 litres per minute



Typical Signal 500 pulses per litre,800 pulses with fast turbine



Pipe Fittings John Guest Female Adaptors 3/8

Material Polycarbonate outer case,acetal resin end bearings,rotor,end fittings

Stainless steel rotor spindle (all approved ‘Food Quality’)



Supplied with 2m connecting cable, plug,boot screw, John Guest fittings, High Speed Turbine.



Manufactured and designed by Drinkbrook

Discount on quanity orders, postage etc

[MOD EDIT: EMAIL REMOVED FOR SAFETY]

 

[Reloadron]

OK, that would work. Let me kick things around a little and get you some ideas. This would be PC based running on a Windows operating system. It would consist as I mentioned of a flow meter followed by a hardware device with a USB interface to the PC. The rest would be software.

Ron

 

[maddave]

sounds good how easy would it be to get the hardware and software

 

[Reloadron]

Shouldn't be too difficult to get the pices & parts. The main item is the flow meters. As I am sure you have seen they come in a variety of flavors and types. Some can be quite pricey while others less expensive. The way I would go about it is along these lines. You have the flow meter:

Signal Square wave,min 90% of supply voltage

Flow Rate Region of 1 litre to 25 litres per minute

Typical Signal 500 pulses per litre,800 pulses with fast turbine

The last line is what is known as the K factor. The number of pulses per litre. We don't care about things like litres per hour we just care about the pulse count per litre. The pulses comprise what is needed for a batch or totalizer counter.

Then we need to get that data into a software routine running on a PC. This is where I would use a device called a DIO (Digital In Out) card. The card would for example take the pulses from the flow meter and pass them into the PC software. That being a DI (Digital In) example. When certain conditions are met that same card would use DO (Digital Out) functions to turn a solenoid valve on or off or other functions. This type hardware is very, very common from a variety of distributors and relatively inexpensive depending on the number of channels used.

The software on the PC would offer you a graphical user interface. This is where you set the customer up when they pay for however litres of brew.

Ron

 

[4pyros]

How many stations? If not to many you can use the PCs printer port.

 

[maddave]

when you talk about getting a flow meter do you mean a meter that will display the number of pulses or What I would call a flow meter sender that sends pulses to the meter when the beer is flowing ?

 

[maddave]

4pyros ........ If its possible for 1 computer to control more than one pump I can add as many ports as needed ideally a pumps

 

[maddave]

could i have more than 1 ido card in computer

 

[maddave]

sorry dio am i right in thinking that this: 8-CH High-Power Relay Outputs & 8-CH Isolated Digital Inputs Card
would run 8 pumps

 

[Reloadron]

sorry dio am i right in thinking that this: 8-CH High-Power Relay Outputs & 8-CH Isolated Digital Inputs Card
would run 8 pumps

No, the number of DIO channels is to be determined per tap or station. For example each tap will have a chennel for pulse input(DI), a channel for an on/off solenoid valve (DO), and whatever to be determined. I likely should not have used the word "card". I would use an external DAQ (Data Acquisition) device running under the USB port.

Now as 4pyros mentioned a tap or two could be run off the parallel port. I discourage doing this for a few reasons. The first is the parallel port is a dying port and most new machines don't even have one anymore. Communicating with the parallel port was a simple task under Windows 98 and through Windows XP with some effort. Using it for an app like this under Windows Vista or Windows 7 is not easy.

Anyway, my choice would be a data acquisition device running on a USB port. That being just my choice. The number of channels needed is yet to be determined. Yes, relays would be used for the solenoid valves used.

Ron

 

[maddave]

just when you think you understand ......... so the 8 ch dio card i have just paid for will not do the job ar well another leson in life paid for now i am looking for a data acquisition device is that rite

 

[Reloadron]

Look, I think you are into a real nice idea. However, let's take some time to think this through. This weekend I should be able to have a basic demo panel where the signals are simulated and you can see what an example of a graphical user interface would look like. The DIO is selected based on several things. The actual piece of hardware will determine how the software is written. This is not a monumentally complex project but it also is not all that simple. I am not a programmer type but can write enough code to show you a demo.

Ron

 

[maddave]

thanks for your help .... thats me rush rush rush .... the dio card is on its way to me so if i can use it that would be good ... but if not al use what ever works ...........once again thanks for you help

 

[Reloadron]

Exactly what card did you buy? Part number, data sheet, link?

Ron

 

[4pyros]

If you ordered a card it must fit in a slot on your computer, if you have more slots than you should be able to use more cards.
As Reloadron said at minimum you will need one input and one output per statshoin.
How many statoins are you going to need?