CTR-500 module reading too many pulses?

[Little_Dave]

Hi.  I am using a CTR-500 module as a totalizer to count the pulses coming from a turbine flow meter.  The flow meter is calibrated for 1 pulse/L and our pump is displacing 5-10 L/min.  The pulse's high state is about 18VDC.

The problem we are having is that when the pulse occurs, the pulse count goes up by 5-40 counts (sometimes more).  The LED on the module behaves properly and matches the pulse output from the flow meter but the reading we get in NI-MAX is not right.  I'm sure this is something simple that I am missing but I can't seem to get it to work right.

I have the feeling that the module is reading many false highs as the pulse is high for a good second or so.  How to I get the module to count only the rising edge of the pulse and ignore the rest?

Any help is appreciated.

Thanks,

Dave

[AnalogKid2DigitalMan]

Dave:

What is the manufacturer and model number of the flowmeter?

I'm wondering if it uses a dry contact switch as the output, this could be 'chattering' (open/closing many times until it reaches a steady state) that the 500 is picking up.

I'm not familiar with the 500 so I can't offer any advise if it can latch on a rising edge.

[Karunya_R]

Hi Dave,

CTR-500 does use edge counting. You can perform a software check to see if it is still at a high and if it is then not do a count and if it is not the increase the count. The green ready light just indicated that the module is working in normal mode and the green status indicator light turns on when the channel is used. Have you tried using a different flow meter with this?