Instantaneous FLOW & totalizing from pulse input

Hi everyone this is my first post here. I have been reading a lot of the posts here regarding totalizing using pulses, however not exactly what I am trying to do. So here it goes. I am working with a flow monitor (Blancett B2800) with a pulse output, 20 ms on state max pulse rate 20 Hz. The monitor sends a pulse every 100 gallons. I need to get the GPM. Processor is Micrologix 1400, using the HSC to read pulses. This might sound easy but my requirements are that I cannot reset the accumulated value of the HSC since the customer wants to add existing data and store until i reaches a high preset. The monitor outputs about 2 pulses per minute, but I can't wait that long to show instantaneous flow rate. I know that I need to count the pulses and divide by the period. x=pulses, t=period, t=t2-t1. Is this right? Or is this easier that I think and making too difficult? How can I get the time between pulses or more importantly the instantaneous flow?

Other requirements are to show total flow (pulses x 100) in a day and a month.

I have been spending a lot of time on this and shortly (yesterday) I have to have a working program. Please help!!!!

your meter gives one pulse every 100 gallons per minute
what is the maximum GPM that this unit is capable of.

If the unit only outputs 2 pulses per minute then the maximum accuracy
is only going to be 100GPM + 100GPM 0r - 0 GPM (1 pulse + 1 or -0)
it will not matter how fast you try to read this
More information is required
I will look at the meter you specified.

According to the info you can preset the operation.
the tantalizer signal is the one you are intending to use.
again what is the minimum GPM and max. GPM+

Min is 100 and max is 1200.

while your still there
are you gong to display a decimal ammount like 0.1 GPM
this would make it easier for calculations

Hi Ian,

Yes I intend to display the flow in 0.2.

I have thought about setting the K factor, this is something that I would have to OK with my customer.

Thanks.

you may not need to change the K factor - this was in the PDF that I read from the I/Net
off hand I dont know if this is needed to be changed