I have 2 belts running at different speeds. How do I setup the controller so that the product is tracked in any case ?
Tracking is so important in this (and other) inkjet controller that you have to understand it 100%.
As a matter of fact, all EditorGTs have a tracker but some controllers really track only by product not enough. We track by the millimeter. It is done by the plugged-in processor card. There is no other controller in the market as integrated as this.
With an encoder (the heart beat) and a photocell (the eye), which are the only elements that allow a controller to “feel”, you can track a product. That is, you can detect a product with a photocell, after that the number of encoder pulses gives you the position of the product.
What you see, is that the red line is at the left of the window. The green points are last min. and max.
This must be done for all elements along the line and is called “timing the line”. The best practice to do this, is to set the controller in Make-Ready mode, to pass only one product through the line and check photocells.
Once done. You may want to pass just one book in production and check the green sync point eye, that the inkjet writes on the book, that the product is in the window of product detect 2, that the gate closes just before the book passes it, and that the stacker ejects the book if you started with a bundle break book.
In long saddle stitchers, you can also just stop the first product at every photocell (depending on whether you defined leading or falling detection) and check whether the first product is in the window, was written, the gate, etc.
During production, you’d better produce a quality book to check that everything is still O.K.
Absolutely everything that happens in the controller:
· Print-go to inkjets
· Trigger to Camera or barcode reader
· Gate and stacker handling
· Positions of photoeyes
is based on the right handling of tracking. Thus, it is of utmost importance, that encoders (cannot be speed dependent, no slipping) and photocells (no double or false triggers) are well installed and work properly.
Jogging Test- Handover product to next tracking segment
If you understand below, you understand tracking !
The ultimate test whether you positioned your photocell right is the “Jogging Test”, another test is to change the speed of belt 2 in relation to belt 1. Let’s assume that you have a first belt that you can jog and a second belt that is always running (like happens with stackers), that is both segments run independent from each other.
Now, where do you have to place the photocell ?
To answer that very important question, let’s assume that the distance between product detect 1 and product detect 2 is 1000 mm, the product is 150 mm wide. Well, if one opens the window at 950 mm for 100 mm that would do it right ?
Is that how the tracker behaves ? Yes, but…
The tracker will detect a product at product detect 1 (+edge), then count 950 pulses and open a window, if product detect 2 is set to positive (or raising) edge, the product is going to be handed over to the second belt when product detect 2 sees the product !
Now, please imagine that you jog belt 1 until the product is just before product detect 2, may be distance 980 mm. The tracker will have its window open, ready to detect the product and hand it over to belt 2.
Nothing has happened above yet. The window is open but it has not been seen by product detect 2. Hence, the tracker thinks the product is still on belt 1.
Now, let’s assume that we jog to 1020 mm and stop belt 1, belt 2 is turning and the shaft encoder 2 is giving pulses. The product is still on belt 1. What will the tracker think here ?
Well, the tracker thinks the product is on belt 2 and already sliding down to the customer. If it was the end of a bundle and you had to give a stacker signal, the bundle will come out but the last product in the bundle would still sit at the end of belt 1. THIS IS WRONG !
Therefore, if you use the positive or raising edge of product detect 2, make sure that you place product detect 2 into belt 2, and adjust the distance. You have to place the photocell where belt 2 has taken the product and transports it already, close the window after.
Conversely, if you use the negative or falling edge, make sure that you place product detect 2 where the product sits on belt 2. Of course, the window open is less than 950.
Note: make sure to load tracker 2AV in the tracker, at least version 3.54A in the controller because there was a bug in the software that the edge at product detect 2 was always set at positive, even if you set it to negative ! If you don’t want to update, use the positive or raising edge version.