6/3/2020 12:17 PM | |
Joined: 6/3/2020 Last visit: 2/11/2021 Posts: 3 Rating: (0) |
Hello community, is my first post here and I really would appreciate your help! I have two 2000 Liter tanks, with a height of 1,57 meters each one, I need to display on the screen the amount of water poured into each tank (in Liters), to measure the flow I have a vortex flow meter sensor (5-85 L/min) with a standard output (4-20mA) for each tank; I would like to have two operation modes: manual and automatic; they will be selected with a two position selector switch.
I have been checking the forum, reading similar solutions with pulse flow meters and level for tanks, and after it I assume it's possible to make it using the Logo, however I have a few questions: I suppose as soon as the pump turn on and during this time I need to save the parameterized value of my sensor each second in some kind of analog variable, and somehow each second add this value to itself, obtaining the volume in the tank. However,how could I do this?do you have any suggestion to make it easier?Also, it's important the accuracy (for example, if I obtain 2010 Liters instead 2000 it is a critical problem and wouldn’t be a good solution) would I have some kind of cumulative error doing it in such way? or some processing overflow? would be really helpful if you show me the way. Would be easier to solve this with an S7 PLC, as is the first time I use a Logo I'm a little bit confused, however, would be a really cheaper solution to use the Logo, and I really would like to do it. Attached is the flow-meter datasheet and the no linear tank Dimensions. I'm using a 0BA8. Thank you so much. AttachmentDocumentsFlowMeter.zip (275 Downloads) |
Last edited by: Carlos&Lopez at: 06/03/2020 12:18:33Last edited by: Carlos&Lopez at: 06/03/2020 12:58:20 |
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6/4/2020 10:18 AM | |
Joined: 2/22/2008 Last visit: 8/6/2024 Posts: 2698 Rating: (207) |
Maybe the program in attachment is a base for you. The only way to minimize measurement faults are high accuracy sensors and also analog inputs, but the Logo only have 10 bit resolution. Additional the Logo only have 16 bit integer arithmetic (15 bit + sign). If you make calculations with the arithmetic block, then internally is used floating point arithmetic and rounded at the output, this will debase the accuracy with bad values. The attached program has no calculations. Your sensor with 5-85 l/min is ideal, because the difference (80 Liter) has a Logo value difference 800. There are no roundings to get the flow with 1 decimal. This value is added in B003 every second. To avoid overflow the sum is checked for more than 599 (600 = 60 l/min = 1 l/s). In this case the Liter counter will increase and also the value 600 is subtracted from B003. The subtraction is done up to 8 times within a second, if B003 reaches 600, 1200, 1800, 2400, 3000 and so on. There is also an easy manual / automatic mode integrated, try it out in a simulation. Regards, Scorp AttachmentTank1.zip (323 Downloads) |
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