Advice on creating frequency measurement

[Jhav]

I am using a IO-D16A3-RO16 expansion module for its 2 HSC but it does not come with the option to have the HSC and frequency measurements, so i will have to create my own frequency measurement  so far i have a reseting a timer at 1 sec sampling the counter. is there a way to store the sample  and subtract it from the last sample taken? anyadvice wold be appreciated .

[Flex727]

Try using the Store and Subtract functions.

All kidding aside, is there something you're trying to do that I'm missing?

[Jhav]

I am just new to unitronics and have not programmed a PLC since school 11 years ago. This forum is a good resource. I am trying to get flow rate in GPM. 

[AlexUT]

1. Look at following article:

https://support.unitronics.com/index.php?/selfhelp/view-article/calculate-totalizing-or-integral

2. Expansion module you use IO-D16A3-RO16 is relatively "slow", as it ise serial type of communication with PLC.

But if you read sequential values at fixed time interval, let's say, 1 sec, it will work for you.

2. Other way is to use "Frequency Measurement" option:

This can give you estimated frequensy, proportional to flow, at selected time interval.

You can use MI or DW for both, High Speed Counter and for Frequency Measurement.