Ladder Logic Ideas?

[AmazingTrans 0]

Hey everybody... I have a logic question and might need some help in thinking about this. This machine is a splicer used for printing industry. I have 2 rollers and each of them have 2 sensor. One of the roller have a small plate on it and when the sensor detects the plate it means the roll makes 1 full turn. On the other hand, the other roller is a smaller roller that have 120tooth and xcm in circumference.The paper goes from the Big roller to the small roller, and whenever the big roller sensor detects the plate, the program will start counting the small roller tooth, then estimate the amount of paper that has gone through when the big roller sensor detects the plate again. Then the diameter will be store at Bit[1] and display at the HMI. The diameter of the roller will be resetted when it take the action of splice. The formula for finding the amount of paper has gone through is "Amount of tooth for 1 turn / 120tooth * xcm ) How can I program in an efficient ladder logic way? Hope someone can help me on this.

[TimWilborne 108]

What type of controller are you using

[Spedley 0]

I'm not quite cler of the machines operation. There is 1 big roller which has a sensor which can detect a full turn and a small roller which detects 1/120th of a turn. Is the paper wound onto the small roller or does the small roller feed the paper at a constant speed to another part of the machine? I presume the small roller feeds the paper at a constant speed (I can't think of a use for gradually decreasing roll sizes otherwise). If I presume correctly then what you want is to count how many teeth pass on the small roller per revolution of the large roller - which would allow you to calculate how much paper is left on the large roller. 1) When the Large Roller sensor comes on enable the count for the Small Roller sensor. 2) The Large Roller sensor will then go off but the count should continue until ... 3) The Large Roller sensor comes on again. 4) Copy the value from the Small Roller Count and perform your diameter calculation and send it to the HMI screen. (Note, this is logically the last step but it makes more sense to put it at the start of the program - otherwise the count will be reset before you make a copy of it) And the cycle starts again ... Is that about right or have I mis-understood?

[AmazingTrans 0]

I'm Using L32E CompactLogix.

[AmazingTrans 0]

Spedly; There is 1 big roller which holds a roll paper and it unwinds with the help of another machine name Infeed pulling the roll of paper. The big roll of paper goes through this small roller which detects 1/120th of a turn. The pulling of the paper from the big roll depends on the overall printing press machine. It can goes up to 2000 foot per minute. And yup you are right. Another problem is. I want to keep the 1st diameter of the roller, and then subtract the current roller diameter so that I know how much paper is left. How should I write it in order that the program keep the 1st diameter and the program doesn't keep on overwrite the 1st diameter?

[botteman 0]

My first post on this forum java script:emoticon('', 'smid_2') .... What AmazingTrans apparently has is an unwind stand with the paper being pulled off by another driven roll. The unwind stand shaft has a single pulse per rev marker. The other roll he mentioned is a small roll acting as a "measuring wheel" with a certain cirumference and 120 pulses per rev. He wants to count the measuring wheel pulses per each rev of the roll of paper to determine paper length, then calculate the current roll diamater and compare that value with the starting diameter. Right AT ??

[botteman 0]

As a follow-up to my previous post I don't know if this is related to what you need, but check out this recent thread ... http://forums.mrplc.com/index.php?showtopic=6678

[AmazingTrans 0]

bottleman, yup you are right about hte function that you mentioned. About the link u gave me, i guess it will be a help much later. The other link determines the diameter of a roll by relating with the line speed and motor. I have idea on how to calculate the roll of the diameter because I can do a ratio of the big roll with the small roll. With every tick from the big roll, it is one turn, and with the amount of pulses that the small roll have gone through & also the circumference of the small roll, we're able to calculate the total length that have used, & from there we can use the formula C = pi*D. my problem was dealing with the counter, where I'm not sure when should I reset the small roll tick counter, and on the other hand b4 it resets I also want to calculate the diameter of the roll. Apart from that, I also need to keep the 1st roll diameter so that I am able to calculate when is the nxt time to splice the roll when the roll reaches 6cm. In my calculations I will be calculating the caliper of the paper, & the speed of the press pulling the paper too.

[Spedley 0]

I think this covers your basics. It should at least get you started but you need to consider how many pulses from the small roller there are for one pulse of the large roller - if there are too few then basic counts like these may be inadequate. Edited 16 Feb 2006 by Spedley