kurt.brinker
Member
This is the scenario.
We have 3 fluids to mix. One fluid is under constant pressure and the other 2 are pumped out. We have flow meters on all three lines right where they leave their respective containers. The flowrate of the pressurized fluid will vary (not alot, but a few GPM) and I want to incorporate PID loops for the pumps on the other 2 liquids so that the flowrate of fluids 2&3 is always equal to the flowrate of fluid 1.
I am thinking i should ensure the scaling on all three meters is the same and then take the 4-20mA signal from the first flowmeter and have that value create the setpoint for the other meters. The pumps will then increase or decrease acordingly. ( obviously, The PV for the loops will be the 4-20 from the 2 meters. )
Also i am using SLC 500.
One more question. WHen i recieve the 4-20, should i immediately scale it 0-16383 and use that value or leave it as 3277-16383.
I'm not looking to have this programmed for me or anything of that nature. I was somewhat thrown into this position and i am burning the midnight oil every night learning as much as i can. I was supposed to be studying under our main programmer but due to alot of personal problems, he hasn't been around much. Anyway let me know if there is an easier way or if you need a better explanation/
We have 3 fluids to mix. One fluid is under constant pressure and the other 2 are pumped out. We have flow meters on all three lines right where they leave their respective containers. The flowrate of the pressurized fluid will vary (not alot, but a few GPM) and I want to incorporate PID loops for the pumps on the other 2 liquids so that the flowrate of fluids 2&3 is always equal to the flowrate of fluid 1.
I am thinking i should ensure the scaling on all three meters is the same and then take the 4-20mA signal from the first flowmeter and have that value create the setpoint for the other meters. The pumps will then increase or decrease acordingly. ( obviously, The PV for the loops will be the 4-20 from the 2 meters. )
Also i am using SLC 500.
One more question. WHen i recieve the 4-20, should i immediately scale it 0-16383 and use that value or leave it as 3277-16383.
I'm not looking to have this programmed for me or anything of that nature. I was somewhat thrown into this position and i am burning the midnight oil every night learning as much as i can. I was supposed to be studying under our main programmer but due to alot of personal problems, he hasn't been around much. Anyway let me know if there is an easier way or if you need a better explanation/