Material tracking

I want to track the progress of material through a rolling mill as it passes a sensor. I have tried dividing the current speed of the mill (M/MIN) by 600 to create a "factor"and using a 100ms system bit add the factor every 100ms to a total but the results don't seem to be correct. I have tried this on a simulator on my laptop. Could it be the simulator/laptop scan time throwing things out? Any better ideas apprecited. Using Unity Pro software Quantum PLC.

Thats similar to tracking that I do.

Usually I use some sort of tracking signal, like a tacho or proximity picking up on a wheel etc, but also have used a timed signal.

If you use a timed signal then you have to be confident that the material is moving at a constant speed and tie in the running signal.

There are many methods, all include synchronising the position with photoeyes and then incrementing the position afterwards, by incrementing a count or by shifting bits or registers.

Hello Pauly,

Rogerstone I presume?

The method to calculate length by integrating speed relys on the material actually travelling at the speed that you think it should is. I use this method quite a bit in web handling applications.

The other method to considder is putting a prox sensor with a flag on a roller driven by the material and counting pulses; try to maintain an even mark to space ratio for the flag.

Nick

tracking data

At one time we used to cut a lot of wood. We tracked logs and cut lumber through the whole mill. If your drives are speed controlled they need an encoder or prox wheel pulse encoder to feed a speed signal into the PLC. At each drive transition you need a photo eye to confirm the product is where it is suppose to be. The more eyes the more accurate the position feed-back. In PLC memory you identify the product with a 16 or 32 bit word as it enters the first drive. Using the prox wheel encoder and the eyes, you Bit shift the PLC word through a virtual process in PLC memory. Bit shift left is forward and bit shift right is reverse.
The PLC scan time is not an issue with your process. I would think your speeds are well under 160 feet/ min. Even the slowest and oldest PLCs can handle this. We used Allen Bradley PLC2/30 for 180 feet/min and it sorted as well as tracked the product. Here is a starting point. Think how your product moves and what data you need to know about the product. How long is the product moved? If only a short distance, then you can simplify the program. Hope this helps a bit..