Help with harware selection

:book:Hi all, Been a lurker for a long time, now I need some advice if that's ok.

I have been asked to build a machine, and although it is a very simple machine im wary of how to start because I cannot decide which way to go .
The machine will pull from a reel a length of film, say 200mm. Now, it will do this everytime the upstream machine gives it a signal,(in the order .25HZ). Now it would be simple to program a pulse generator in the plc to give x amount of pulses on one of the high speed outputs. I could wire that into the stepper motor driver card and it would work very well.
The problem is the I need to change the length of film depending on the batch. so I will need a HMI and a way of making a variable change the pulses, (I don't know how to do that but I assume it can be done )
This is not the only way of doing this, I could obviously use a dc motor and an encoder and just stop the motor when enough film has been fed.
and then there is the question of PLC+HMI hybrid all in one units, and also there are stepper motors that have the driver , and controller built in!

there is so much option these days im getting swamped with too much info.

How would you do it, and why ?

Hope that isn't too much of an open question.

Thanks in advance for any help which comes my way..
Gareth

My instinct is to use a stepper or servo motor with an integrated amplifier that has enough control capability to use a tiny HMI or discrete inputs to change the index distance.

I do reel feed applications with Animatics SmartMotors. They are well supported in the US but I don't know about the UK.

Another good integrated controller/motor is JVL. They have a little "SMC75" controller board with a "nanoPLC" that could take Modbus over a serial interface or use discrete I/O from something like a thumbwheel to select the distances you need to run.

Schnieder MDrive steppers with their little embedded controller might also fit the bill.

If you are doing motion have a look at the Omron NJ - it is designed as a machine controller and uses EtherCat to the drives and I/O devices. Really fast from what I have seen. They have motors and controllers too.
Have not tried these as I do not do this type of machine control but a few friends do and they swear by it.

Thanks for the advice so far, ill look at those parts later. they do sound very useful.

Some servo cards have pre-configured set points. All your PLC or controller would need to do is send the program number in binary or Bus enabled fashion. If accuracy is important use a servo. Otherwise use a Vector VFD with encoder mounted motor Or a stepper these you would have to use PWM. Some Vector VFD's also have pre-programmed steps.
Other option would be a linear drive from Festo with a gripper system. So many options but you need to weigh up accuracy vs.cost.