Design the Logic

[Muhammad Daniyal 0]

Good Day, Dear friends, My Problem related with the turbine Flowmeter who has the pulses output with respect to flow of fluid. E.g 10PULSES represents the 1 litter/min. the flowmeter does not have any converter that convertes the Pulses to standard Analog signal. So i want to convert the Flowmeter pulses in Analog format or any scalabel form by designing in the Ladder Logic. if anybody have the idea of femiliar with this scenerio kindly guide my or help me through your experience, therefore i could complete this task. it is requested for the quick responce by you people. Thanks & Regard. Daniyal

[TConnolly 13]

Many PLCs have a high speed counter (HSC) input which will give you the frequency of input pulses. Check your PLC manual to see how to use HSC functions. Since you are in the AB forum I'll assume that you have an AB PLC. You can get AB manuals at http://literature.rockwellautomation.com Which model of PLC are you using?

[Muhammad Daniyal 0]

I am using MicroLogix 1500, it is true that i should use HSC, but do u have any idea of the conversion formula from Pulses to Analogue format.

[BobLfoot 302]

If you don't have it the whole 1500 manual is here - http://literature.rockwellautomation.com/i...rm001_-en-p.pdf Now lets tackle an example: Given 1 pulse = 0.01 gallons so 600 pulses in a minute means 6 gpm. Given flow rate will be between 0 and 40.95 gpm or 0 and 4095 pulses per minute. Analog output of 4ma will reprsent 0 gpm and 20 ma will represent 40.95 gpm. Using an STI routine you capture to N7:1 the ACC of the HSC and reset the HSC every second. Now you take N7:1 in pulses per second and multiply by 60 to get pulses per minute in N7:2 N7:2 will be between 0 and 4095 due to design. This can be sent to most AB Analog Outputs {note - I am not experienced with the 1500 analog options}. You'll get your 4-20 ma for 0 to 40.95 gpm. Now obviously you can see where you'll need to scale and modify the equations to get 4-20 from your particular meter and arangement.

[Muhammad Daniyal 0]

dear Bob, sorry for late reply, i could not understan what you have written, it may better if you make an example in logic for my assitance. i never use the Function of STI and HSC before and this the first time that i am dealing with them. kindly if do this in favour for me or any other source for my better knowlegdement. thanks and Regards

[BobLfoot 302]

I am home for a long weekend and no PLC Software available right now. Anyone who can lay down some sample code please assist also.

[Muhammad Daniyal 0]

I am home for a long weekend and no PLC Software available right now. Anyone who can lay down some sample code please assist also.

[BobLfoot 302]

Buried again today - we blew out a 500 MCM feeder conduit, but that's another post. I did whip up a quick trial program. Caveat Emptor however, I have no experience with STI or HSC in the 1500 and the setup is just SWAG. You'll have to debug from there. GPM_TRIAL.RSS