please be gentle with me because sometimes i don't explain things well enough!

but i will try.

I have a oven with 2 zones going from right to left:

<<<<<< ZONE A <<<<<<<<<<<<<< ZONE B <<<<<<<<<< 

I have to control a gate at the end of conveyor (this is controlled by others), the product comes into the oven and enters through ZONE B through to ZONE A and this will start a dwell time of 10mins (example) then release the product.

But if i have a product in ZONE A and another product enters into ZONE B then i need to allow the time to be adjusted so that for example if the product in ZONE A is released and the product in ZONE B has already been in the oven for 5 mins then moves into ZONE A, i then have to release the product when the total dwell time is complete.

I have not used shift registers in this way before and i wondering for some pointers in the correct way of doing this, if indeed this is the best way of doing it.

Thanks

If i have not explained very well then please ask for further information.

current inputs and outputs:

I1 = Zone A Sensor

I2 = Zone B Sensor

Q1 = Gate Solenoid

edited: added inputs/outputs

Hi, could you share your program?

What is the LOGO are you using? What is the logo softcomfort as well?

Not sure uploading the program will help, this part of the program is not completed.

it is not 100% clear why you would want to use a shift register. Is it not possible to control the gate to release a product when the gap between products is enough? 

Consider making a hand sketch of your problem and indicate the positions of the x2 sensors and x1 gate. I assume the conveyor is under the control of the other contractor. I assume the speed of the conveyors are kept constant.

Is the average gap between products more than the time that the minimum 5min gap? What prevents a build up of product at the gate? Is it possible for the gate to separate two products from one another?

Sorry i should have been more specific, the track has powered carriages on it that are controlled by others and the gap between them is controlled by a laser measuring device that works out the spacing/speed between each carriage.

what i proposed to do it operate a flag with pneumatic solenoid so this is placed in front of the sensor to stop the carriage,

This bit is fine but the trouble i have that there are 2 zones from right to left 

<<<<<<< Zone A <<<<<<<<< Zone B <<<<<<<<<<<<<<

The carriages enter from the right and move into Zone A and stop and the then start a dwell time of say 20 minutes but say after a carriage has been in Zone A for 15 minutes and another carriage enters into Zone B and after the dwell time of 20mins has elapsed the carriage in Zone A is released and the carriage in Zone B moves forward into Zone A this now needs a dwell time of 15  minutes because its already been in the oven for 5 minutes.

I hope i have explained it a little better, like i say the carriage control is done by others and works well with the laser system in place. i am just unsure how to go about transferring the time etc.

You have a storage for two cars. That does not need a shift register. Use two timers. Have memory bits select which timer is used. For example M1 and M2.

If the car passes the sensor from Zone B -> A then M1 is set when M1 is off. Else have M2 set. M1 lets B001 timer run; M2 lets B002 run. If B001 runs out, open the gate and reset M1. If B002 run out, open the gate and reset M2.

The front car will always have its timer run out first. So have a timer running for each car that enters Zone A. A timer running out means the gate can release the front car.

thedodgy1

fantastic Thanks, that kind of works but i am just unsure where to place the Zone A sensor.

Fantastic? With a "but". And no rating. Ouch!

Well it is not clear which gate you are controlling: (a) Existing Conveyor Stop or (b) Sensor Flag. I am guessing (b) which makes me nervous on how the speed of movement looks like. I may have made a design that would use a cam action that brings the flag in as an ellipse path as to prevent hitting the outgoing car. Then I1 (zone A) would detect the new car which activate the closing of the gate. I1 would detect the car that is standing at the sensor flag.

Same with I2: Detect the car that waits to enter zone A. The timing triggers as the car passes through I2. 

I1 and I2 can then indicate some feedback state of cars waiting to be serviced.

Hard to concretely say anything without proper knowledge of the site. You are the designer, so you will have motivate what is where for which reason.

I did but a thank you, and it is very very much appreciated that you have given me some time.

I will be using sensor at Zone A for the flag opening and i understand your concerns but the way the carriage system works is that the laser level and various other sensors on the system prevent any crashes etc, i only need to control how long its in the oven for because the substrate used is heat sensitive.

Thins is if this was using a S7 -1200 or similar then i think it would not be a problem for me to do with some sort of state sequences. But on the logo sometime you can overthink things.....

Again thanks for the input and if you think of anything else then please let me know.

OFF TOPIC 

thedodgy1

<snip>
Thins is if this was using a S7 -1200 or similar then i think it would not be a problem for me to do with some sort of state sequences. But on the logo sometime you can overthink things.....
</snip>

You are someone with a full bag of experience and knowledge. Yet your response is weak -- which does not suit you. That is said with a tone of encouragement.

You are able and capable to make a program for the LOGO! that delivers a state sequence. Realise that SET and RESET of memory bits is the basis for a sequencer.

Practice in making FBD logics is what stands in your way, in my opinion. There is enough material on this forum and in the Siemens examples to facilitate practice. Consider spending some quiet time to spend time on constructing FBD logics that is unrelated to your many projects. You can even try solving some forum questions. (No need to publish your answers.)

From outside it seems as though the forum is used as a way to 'cheat' on your 'homework'. That may be true or it may false. Just as you are, we volunteers are busy people too. You will not always find answers to your questions. I encourage you to do some practice work with your LOGO! simulator.

If FBD is really your stumbling block - use another brand's controller. I am thinking of the Micro810 from Rockwell as an example. That one is a proper S7-1200 level processor.

Good luck.

I am sorry but i could really do with some help on this, i am finding it very difficult to do what i require, yes i understand the frustrations.

I do understand the logic of the logo and i have made many programs and i only come here for the experience of others and if i am honest, i thought this was the purpose of the forum.

I dont wish to be spoon fed with the answers but i little guidance and if i have not explained myself very good then i can only apologise.

if someone is kind enough to help me then great but i will understand if not.

Again i will try to explain my problem.

The conveyor speed, Stopping and distance is all controlled by others and will have no impact on the below:

I2 = Zone B Throughbeam Sensor

Q1 = Pnuematic Stop Flag for Laser Sensor.

Thanks