In attachement there is a basic explanation of the machine.

It's a cross cutting machine with two axes - roller and cutter. The material is hold on rollers with use of camming rollers driven with pneumatic cylinders, that move up/down following the material front and end tip. Two boards at the same time are present on rollers. Small pieces are ejected when cut, so  a gap is formed.

Two initial problems are:

1.

How to home the axis if two workpieces are present at the same time. Is it possible to make two virtual axes and swap them and link to real axis?

Or, it would be easier to use modulo axis and forget to make it more easier for debugging, because the positions will have some unreasonable numbers.

2.

When the rolllers axis is standstill, the cutting is performed. At this time I can update all cam tracks. I don't fully understand how these tracks are purged out and what happens if I update the cam track with same index. I would require some kind of FIFO for cam tracks instead, or I can update the same indexes of cam tracks?

Marko,

my 2 cents about the second concept:

why do you use cam tracks ? I mean, do you really need a microsecond precision in the output generation toward a special axis position ? I ask this because cam tracks are pretty "dispotic", I mean, to fully use their power you cannot do very much (expecially manipulation their output: if you use the output in a 4 ms program you will loose the microsecond accuracy) and you can have troubles if you need to do particular things.

For point #2 I 'd suggest that you make your own cam track where basically you compare the axis position to the desired window and you set a bit when your position is inside the range.

You can launch this procedure in some ways:

1) IPO clock connected program (useful if you need special response speeds)

2) Timer interrupt task (best thing to do)

3) Background task (deprecated use...)

Regards

Hi.

Some pieces of the control concept are strange to me. Whatever.

1 - I'd go for shifting measuring system rather than homing over and over again. To get rid of problem of multiple boards, position measuring sensor should be placed close to the cutter.

2 - how about controlling your cylinders with help of shift register ? It seems to be more straightforward.

First, I was thinking to go with PLC control and CU320-2, because I will be the first time for me using SIMOTION and it is quite complicated. The reason to choose Simotion is high speed measuring input, cam tracks/ cam outputs and full information on cutter axis.  The cutter is made of light construction and saw blade, therefore in case of stalling the saw has to stop or retract or zero torque, whatever I will implement.

The cam output/tracks seems to me a perfect solution for now, because the TO_axis knows when it will arrive at certain position. The motion profiles of this motion will be mostly triangle (delta) with jerk limit. At the end I still can write my own cam tracks for this, but I am interested to do this with cam output.

As I understood, the TO_measuring input can latch the encoder position on trigger event, no mather what IPO cycle is the value is the same, except it can't evaluate more triggers within one IPO cycle (which I don't need), then I can use this value as an offset for postioning and cam outputs. Further, one 2nd measuring input near saw position will be placed, this because the grip of the workpiece will be consitent, while at the begining a slipery on rollers can lead to wrong reference.

Now, if machine is empty the first board goes into with MC_Velocity, when first photocell is switched change to MC_MoveAbsolute (or Relative) and set up cam outputs (or user program for cams). When the board is approaching final position it will hit the second photocell - home the axis and recalculate the cam outputs, switch to MC_MoveAbsolute overriding the last positioning command.

When the second (and all others until machine empty)  board comes in repeat the procedure, except MC_Velocity step.

Whatever what I will perform, there will be always a problem to update all cam outputs.  

I have speak to mech. engineer. The gap between two boards will be always greater than distance from saw and last roller, so when reaching the homing photocell near saw, the output rollers will be always open, therefore I can disable/purge the last two cam outputs, meanwhile all the others are closed (if photocell is placed in vicinity of the blade).

Therefore I can use homing procedure for easier debugging and also automatic recalculation of positioning profile as well as cam outputs updating.