Hi Friends,
Has anybody got any experience with developing or utilising an algorithm for calculating a flow-rate of powder material, based upon Loss-in-Weight from a weight transmitter. The amount loss of weight rate at the specified time will be PV to my PID block.
The Flow-rate would be used as PV for a PID Loop within a L61, whose SP would be a manually entered value and the OP would be a 4-20mA output to an Screw Feeder VFD.
Is there any special readymade instruction available in Rslogix 5000 Ver17 which could help me in this concern. Or anybody has got any programs which has worked in this application can forward me at tej_sjce@yahoo.co.in
Is there any parameter that i can use with PID to get this done.
If any more clarification required in this concern, Let me know the same.
Thanking you well in advance
TEJ
Full Version: Loss-in-Weight rate algorithm
QUOTE (TEJ @ Aug 26 2009, 09:27 AM) 
Hi Friends,
Has anybody got any experience with developing or utilising an algorithm for calculating a flow-rate of powder material, based upon Loss-in-Weight from a weight transmitter. The amount loss of weight rate at the specified time will be PV to my PID block.
The Flow-rate would be used as PV for a PID Loop within a L61, whose SP would be a manually entered value and the OP would be a 4-20mA output to an Screw Feeder VFD.
Is there any special readymade instruction available in Rslogix 5000 Ver17 which could help me in this concern. Or anybody has got any programs which has worked in this application can forward me at tej_sjce@yahoo.co.in
Is there any parameter that i can use with PID to get this done.
If any more clarification required in this concern, Let me know the same.
Thanking you well in advance
TEJ
Has anybody got any experience with developing or utilising an algorithm for calculating a flow-rate of powder material, based upon Loss-in-Weight from a weight transmitter. The amount loss of weight rate at the specified time will be PV to my PID block.
The Flow-rate would be used as PV for a PID Loop within a L61, whose SP would be a manually entered value and the OP would be a 4-20mA output to an Screw Feeder VFD.
Is there any special readymade instruction available in Rslogix 5000 Ver17 which could help me in this concern. Or anybody has got any programs which has worked in this application can forward me at tej_sjce@yahoo.co.in
Is there any parameter that i can use with PID to get this done.
If any more clarification required in this concern, Let me know the same.
Thanking you well in advance
TEJ
I can't share them due to Corporate Intellectual Property Rules and all but we have prepackaged routines for processing Analog Inputs and Analog Outputs on the Logix 5000 Platform which include a rate of change calculated value for the given analog signal. With my pre-builts I could just send the ROC.Float to the PID.PV and the PID.SO to the Screw Feeder Analog Out.
Let me encourage you it can be done and its based on a timed sample and some subtraction math, but I can't provide a sample of what we use - So Sorry.
You could take a sample say every 15 sec (or any length of time you want,) Get the difference in weight between samples and then multiply that number by 4 (4*15sec = 60sec)
Sample 1: 15kg
Wait 15 sec
Sample2: 12kg
15-12 = 3kg
3*4 = 12kg/min
Just make sure your sample updates fast enough for your PID loop.
Feel free to comment, as i haven't been doing this for very long
Sample 1: 15kg
Wait 15 sec
Sample2: 12kg
15-12 = 3kg
3*4 = 12kg/min
Just make sure your sample updates fast enough for your PID loop.
Feel free to comment, as i haven't been doing this for very long
Make sure your samples are taken long enough apart to be meaningful.
For example, I have a system that feeds product at speeds as slow as 4 pounds per hour. The load cells are calibrated for 0 - 1500 pounds over 4 - 20 mA into a 12-bit analog card. That works out to a resolution of 0.366 pound which, at 4 pounds per hour takes longer than 5 minutes to feed.
For example, I have a system that feeds product at speeds as slow as 4 pounds per hour. The load cells are calibrated for 0 - 1500 pounds over 4 - 20 mA into a 12-bit analog card. That works out to a resolution of 0.366 pound which, at 4 pounds per hour takes longer than 5 minutes to feed.
This is a "lo-fi" version of our main content. To view the full version with more information, formatting and images, please click here.