DavidG

Hi Keith, Thanks so much for the detailed step by step explanation ofthe PID loop.It is really appreciated and it will eliminate the problem that Iwas having in the project.This will help in bringing this project closer tocompletion.I simply can’t thank you enough for your help . Kind Regards, David

Hi Keith, Firstlythanks very much for the responce.Sorry I think that the above question mayhave been a bit too vague.I have already created the input and output lists forthe plant.I have also studied the excellent webinars provided and learned agreat deal from them.I must say the site is excellent and very user friendly.Iam still a bit of a beginner when it comes to using PLC’s but I am constantlyimproving and learning. I have the majority of the screens built for the project andI can do the basic ladder logic such as an input turns on an output.I also havesome of the ladder logic for the input and output level into the plant carriedout and it is working on the HMI screen.The main section that I am havingdifficulty with is to create the ladder code that will control the vsd thatchanges the speed of the rotors in the aeration tank.The vsd will be increasedif there are too high a proportion of solid particles.I was wondering wouldthere be example of how to control a vsd on the webinars or on the forums.Againany help is greatly appreciated and will be very beneficial in my continuouslearning. Kind Regards, David. Rathkeale Waste Water Treatment Plant IO List Created By David Geaney for use in Final Year Project on 24/11/2011 Main Plant Number Component Number DI Number DO Number AI Number AO 1 Inlet Screen DOL 1 Inlet Screen Auto 1 Spare DO 1 Storm Return Flowmeter 1 Storm Pump No1 2 Inlet Screen DOL 2 Inlet Screen Run 2 Spare DO 2 Outlet Flowmeter 2 Storm Pump No2 3 Inlet Screen DOL 3 Inlet Screen Trip 3 Inlet Screen Start 3 PH Level 3 Spare AO 4 Inlet Pump No1 DOL 4 Inlet Pump No1 Auto 4 Sludge Tank Mixer Start 4 US001 Level 4 Spare AO 5 Inlet Pump No1 DOL 5 Inlet Pump No1 Run 5 Inlet Pump No1 Start 5 Spare AI 6 Inlet Pump No1 DOL 6 Inlet Pump No1 Trip 6 Inlet Pump No2 Start 6 Spare AI 7 Inlet Pump No2 DOL 7 Inlet Pump No2 Auto 7 Aeration Tank 1 Rotors Start 7 Spare AI 8 Inlet Pump No2 DOL 8 Inlet Pump No2 Run 8 Aeration Tank 2 Rotors Start 9 Inlet Pump No2 DOL 9 Inlet Pump No2 Trip 9 Storm Water Pump No1 Start 10 Storm Water Pump No1 DOL 10 Storm Water Pump No1 Auto 10 Storm Water Pump No2 Start 11 Storm Water Pump No1 DOL 11 Storm Water Pump No1 Run 11 Sludge Tank Mixer Start 12 Storm Water Pump No1 DOL 12 Storm Water Pump No1 Trip 12 Ferric Dosing Pump No1 Start 13 Storm Water Pump No2 DOL 13 Storm Water Pump No2 Auto 13 Ferric Dosing Pump No2 Start 14 Storm Water Pump No2 DOL 14 Storm Water Pump No2 Run 14 Settlement Tank No1 Mixer Start 15 Storm Water Pump No2 DOL 15 Storm Water Pump No2 Trip 15 Settlement Tank No2 Mixer Start 16 Picket Fence Thickner DOL 16 Picket Fence Thickner Auto 16 Submerged Pump at Sludge Lifting Wheel Start 17 Picket Fence Thickner DOL 17 Picket Fence Thickner Run 17 Spare DO 18 Picket Fence Thickner DOL 18 Picket Fence Thickner Trip 18 Spare DO 19 Aeration Tank 1 Rotors VSD 19 Aeration Tank 1 Rotors Auto 19 Spare DO 20 Aeration Tank 1 Rotors VSD 20 Aeration Tank 1 Rotors Run 20 Spare DO 21 Aeration Tank 1 Rotors VSD 21 Aeration Tank 1 Rotors Trip 21 Spare DO 22 Aeration Tank 2 Rotors VSD 22 Aeration Tank 2 Rotors Auto 22 Spare DO 23 Aeration Tank 2 Rotors VSD 23 Aeration Tank 2 Rotors Run 23 Spare DO 24 Aeration Tank 2 Rotors VSD 24 Aeration Tank 2 Rotors Trip 24 Spare DO 25 Ferric Dosing Pump No1 DOL 25 Ferric Dosing Pump No1 Auto 25 Spare DO 26 Ferric Dosing Pump No1 DOL 26 Ferric Dosing Pump No1 Run 27 Ferric Dosing Pump No1 DOL 27 Ferric Dosing Pump No1 Trip 28 Ferric Dosing Pump No2 DOL 28 Ferric Dosing Pump No2 Auto 29 Ferric Dosing Pump No2 DOL 29 Ferric Dosing Pump No2 Run 30 Ferric Dosing Pump No2 DOL 30 Ferric Dosing Pump No2 Trip 31 Settlement Tank No1 Mixer DOL 31 Settlement Tank No1 Mixer Auto 32 Settlement Tank No1 Mixer DOL 32 Settlement Tank No1 Mixer Run 33 Settlement Tank No1 Mixer DOL 33 Settlement Tank No1 Mixer Trip 34 Settlement Tank No2 Mixer DOL 34 Settlement Tank No2 Mixer Auto 35 Settlement Tank No2 Mixer DOL 35 Settlement Tank No2 Mixer Run 36 Settlement Tank No2 Mixer DOL 36 Settlement Tank No2 Mixer Trip 37 Submerged Pump at Sludge Lifting Wheel DOL 37 Submerged Pump at Sludge Lifting Wheel Auto 38 Submerged Pump at Sludge Lifting Wheel DOL 38 Submerged Pump at Sludge Lifting Wheel Run 39 Submerged Pump at Sludge Lifting Wheel DOL 39 Submerged Pump at Sludge Lifting Wheel Trip 40 Output Sump Level 41 Output Flowmeter 42 Spare DI 43 Spare DI 44 Spare DI 45 Spare DI 46 Spare DI 47 Spare DI 48 Spare DI 49 Spare DI 50 Spare DI

Hi all members, I am a college student who is carrying out a final year project using visilogic to design a control system for a sewage plant. I am having trouble with the programming and ladder logic side of the project. I was wondering would any member have any helpful information on this area. Any help would be much appreciated. Thanks.