Counting pulses with standard digital inputs

[Kevin Wynne]

Hi,

I need to connect several flow meters that output a low frequency pulsed signal. I can easily do this with the HSC ports but they are limited in number and the frequency I need doesn't warrant their use. How can I use the standard digital inputs to count the pulses sent from the flow meters?

I plan to use a V120 to do this.

Thanks

Kevin

[AlexUT]

To count pulses in Ladder code, input signal, either 0 or 1, should be detected during 3 or more scans.

*Take a maximum scan time.

B.R.

 

[Joe Tauser]

1 hour ago, Kevin Wynne said:

flow meters that output a low frequency pulsed signal

Be a little more specific on this.

I would step up to a V130 as it allows you to run a 1.25 ms interrupt routine.  If you use Immediate Inputs in this routine and increment your pulse counters there you get a pseudo-HSC input on all your on-board inputs with a frequency response of 400 Hz.

Joe T.

[Kevin Wynne]

Hi,

So I guess the question now becomes how do I set up the interrupt routine?

Kevin

[Joe Tauser]

Type "interrupt" into the search box in the Help and all the answers will be revealed....

If that doesn't work post your code here and we'll hack one in for you.

Joe T.

 

[Kevin Wynne]

Thanks

[Ausman]

Kevin, in addition to what Joe has said re the actual frequency  which is very relevant to whether the plc will handle things properly through normal inputs, have a look at this post and also the entire topic to get background.  It might be exactly what you need.

cheers, Aus