PLC encoder sync question

Hello,
I have a question regarding the synchronization of two pulses. Basically what I have is a PE that is blocked by a small pin for every 5 inches of belt travel. The distance is always a constant 5 inches of travel before the PE gets blocked. Then I have an encoder that gives me a pulse about every 6 inches or so. I am not 100% sure on the resolution of the encoder yet. The Encoder is mounted on the same belt that the pin is located on. What I need to do is come up with a method of synchronizing the encoder with the pin pulse. Basically what I am looking for is a way to tell how far in front or behind the encoder pulse is from the pin every time I receive a signal from the pin and encoder.

I am using a RS Logix 5000 processor for this application. The processor is currently running a program where the pin and encoder are not synced. I am assigning a tracking position on the belt for every encoder pulse, and since each pin signal tells me that a 5 inch slot of the belt has passed, I sometimes miss assigning the leading position of the package with the pin because the encoder pulse may come late. I need to come up with a resolution without changing to any type of motion control application

Any help on this issue would be greatly appreciated.

One possibility might be to feed the encoder into an FPD PMUL block, and reset (initialize) the block every time the pin comes around. Run the instruction in absolute mode, and save the delta on the rising edge of every reset trigger.

How accurate do you need to be?
How fast is the process ? One pin per minute or 10 per second
Are Both the Pin and the encoder fixed on the belt?

What is driving the Belt - PF70, PF700, Servo? and how are you communicating with it? Analog, Control Net?

I've had to do something similar and ended up telling the client that they were wasting my time and their money - They ended up replacing the encoder so that they had a pulse per 0.01 of an inch and installed a M02AE module - I believe that you could get the same functionality with an HSC card if you did not need high accuracy.

A simple picture of your layout and problem could assist greatly (more A$$-u-ME problems)