Kind of Input for a Flowmeter ( PULSE )

Hello everyone, i have a flowmeter that will give a pulse for each 2L. I want to know what kind of input i have to use for programming in an S7 1200. (This input will further be used with a counter also )

Thanks !

You must consider your rate of flow. This will determine how fast your input is being put into the plc. How long is your pulse for the 2L?
Once you know your rate you can determine if a normal input on the plc can be used or a high speed counter.

Regards,
Garry
http://www.accautomation.ca

In any case, I would go with the high speed counter input, it should make your life a lot easier.

https://cache.automation.siemens.com/dnl/zE/zExNDk5AAAA_41127453_FAQ/41127453_S7-1200_HSCs_e.pdf

@ gclshortt
In fact the required flow for the pulse is not yet determined, aproximatively it would be 2L, when you ask how

How long is your pulse for the 2L?

Click to expand...

is it the time between each pulse ?

Thanks for the link

@ boneless
In my process i currently have 6 high speed counter its a 1214C DC/DC/RLY, and i have to get the total flow for 6 tanks from 3 flowmeters. 1 among 2 tanks will be using the flowmeter , not the both together. In the process, i will have to prepare for spare tanks also.

Do i need 6 HSC for my tanks. I will have to get an individual total flow for each tank at the end of the day.

i was planning to use normal counter in my program, in case future tanks will be added to the program.

As per @gclshortt i have to find out my flowrate to determine what kind of counter i will be using.

Still i want to know, if i will be using a normal counter, can I use the flowmeter input directly to the counter block?

Yes, If the flow rate is not quick then you can use the normal inputs to a counter. Do this over time and you can tell rate.

If you have a 5msec scan time of the plc, then in one second your PLC will scan 200 times.
1sec / 0.005 = 200 times
So as long as your signal is more than approximately 10 msec. (This gives the signal a full cycle) I would go with a normal input. This would give you 200L a second based upon 2L per pulse.
This is assuming that you receive one pulse every 2L.

Regards,
Garry
http://www.accautomation.ca

To get a completely accurate answer, you need to know three things:
- The maximum flow rate through your flow meter
- The maximum scan time of your PLC
- The maximum input frequency of your hardware input

Once you work out your maximum flow rate, you can calculate how many pulses per second you will be getting on the input. Then you can calculate the time between pulses.

If the time between pulses is less than (or close to) your maximum PLC scantime, then you will need a high speed counter.

If the number of pulses per second is larger than (or close to) your maximum input frequency of your hardware input, then again, you will need a high speed counter.

If neither of those cases are true, then you do not need a high speed counter and can do it using normal counter logic in the PLC.

Thank you all, as soon as I get the above information, I will keep you updated.

I will be using a HSC.... as more changes were added to the process.
HELP on HSC please !!!

Hi everyone, i would like to know how can we very the logic to a HSC, how can we simulate it ?

It depends on the PLC type, but a HSC is ususally ENabled by a particular command or group of commands.

This may be over-simplified, but An HSC runs independently of thw PLC's CPU and isn't affected by scan time. They can often be set to count up or down. The ACCumulated value is compared to a HIPreset or a LOPreset and a High Preset Reached or Low Preset Reached bit is set when the ACCumulated value reached the preset.Think of an HSC as a hardware counter that has been incorporated into the PLC.

Yeah I would recommend a high speed counter. Also on the other note he brang up: 6 tanks 3 flow meters. 1 per 2 tanks only 1 tank s used at a time. well basically.to have a total to a tank you need to know which tank is selected. whether it be manual entry or preferred would be valve position sensors or just the plc at least knowing which tank is selected (2 Control valves, only 1 open at any time)

@ rguimond
The PLC i am using is the 1214C DC/DC/RLY.
I would like to know even if it is a '' hardware component '' is there anyway to test if i correctly assigned the parameters of the HSC and how to know it is working ?

Thanks