Can I collect the pulse data using Field Point?

[zl]

I have a water flow meter, which outputs pulses. I use a counter to connect it and read the data. Now, I want to read and save the data in the computer using LabView and Field Point. I think this can be done if I can collect the number of pulse. I am wondering how to do that.

Thanks.

[Marni]

Please take a look at this post.

[zl]

Marni,

Thank you for your help.

I have a FP-AI-110 and I tried to use it to get the pulses. Was it aproporiate? Do I have to buy a FP-QUAD-510 or FP-CTR-500 module?

If I need a FP-QUAD-510 or FP-CTR-500 mudule, how can I decide which one I need?

Thanks.

[zl]

Thank you for your help.

I have a FP-AI-110 and I tried to use it to get the pulses. Was it aproporiate? Do I have to buy a FP-QUAD-510 or FP-CTR-500 module?

If I need a FP-QUAD-510 or FP-CTR-500 mudule, how can I decide which one I need?

Thanks.

[zl]

I have a FP-AI-110 and I tried to use it to get the pulses. Was it aproporiate? Do I have to buy a FP-QUAD-510 or FP-CTR-500 module?

If I need a FP-QUAD-510 or FP-CTR-500 mudule, how can I decide which one I need?

Thanks.

[Marni]

Dear Zl,

Counting pulses is much easier with the FP-QUAD-510 or FP-CTR-500, but can be done with the FP-AI-110.  You can't directly count the pulses with a FP-AI-110, but you can do it in software. Bring in the data by doing a normal read. Then, using shift registers, if the previous voltage is less than .8V (low) and the current voltage is more than 2.5 (high), increase the pulse count. I have attached a program that shows what to do with the data once you bring it in. I took the data from an array outside the while loop, but your data will be brought in one point at a time inside the while loop. One thing to take note of, since Fieldpoint brings in data at 1 kS/s, this will only work with pulses slower than 500 Hz. The farther the duty cycle is away from 50% duty cycle, the slower the signal must be in order to catch the pulses correctly. Please let me know if you have any questions. Have a great day!

Sincerely,

Marni

PS- Please only post question once.

[Aaron_G]

Marni,

The FP-AI-110 module only acquires data at 1/2 Hz to 5 Hz depending upon filter settings. The fastest rate is .173 seconds with no filtering (~5 Hz), which means he can not measure any pulses that are faster than 2.5 Hz. It would be much better to switch to a [c]FP-CTR-500 or [c]FP-CTR-502 module depending upon the signal characteristics.

Regards,
Aaron

[Dawei]

Hi all:

I have some problems about FP-CTR-500 when I was trying get pulse on the flow rate.

From my FP-AI-112 (voltage sensor), I know that the voltage in the loop is 5V, and it drop to zero and came back to 5V when the flow volume reach some point.

I have no idea about how to set my channel in this case, the value from my FTR-500 is always zero. Can anyone please teach me?

Thank you

Dave  

[Aaron_G]

Dave,

The [c]FP-CTR-500 module has a maximum On Voltage of 10 Volts and a minimum Off Voltage of 6 Volts. With a 5 volt signal, your signal is always below the 6 Volt Off threshold and is always considered off by the count circuitry. In order to guarantee the signal is counted, it must exceed 10 volts (the 6 - 10 Volt range may be registered as either case depending upon manufacturing variances and environmental conditions). You will need to boost the signal voltage in order to use the [c]FP-CTR-500.

Regards,
Aaron

[Dawei]

Aaron:

Thanks for your response, I will amplify the voltage.

Can you also teach me about the other problem?

According to usual manaul:

"when the voltage accross Vin and COM is 10V or greater" current flow through Vin and turns on the optoisolator, registering in an ON state for the channel. When the voltage across Vin and COM is 6V or lower, current does not flow through Vin and the channel is in the OFF state."

What if my case is opposite. 10V or greater is off, 6v or lower is on. Can I do that without adding additional hardware?