hi all.

In one system I have 5 transporters which moves bag. from transporter 1 to transporter 5.

I write some code to detect current position of bag and move to next transporter. Every transporter is equiped with one photocell to detect bag on it. (attached image)

My code look's complicated, so I need idea how to do this on simplier way.

And picture...

Circles is position of photocells.

hdhosseini

Hello,

Just to point out some consideration for your program.Why you don't use a single conveyer belt to handle all transportation needs you want.If we considered it is obliged by design, using sequential control as you have done is wise as any interruption can be handled easily and production resuming can be done without too many manual intervention of operators.

It is also possible to do the same project with sequence of edge detectors , with small programing labor ,while interruption handling needs  too many interventions of operators.Test your codes with simulating module/ real machine and if it works in any situation/interruption, you can use it as your final test code.

I hope this helps,

hdhosseini

 Thank's a lot. But how to do that with sequence of edge detectors???

System is already designed with 5 conveyors.

Hi

I had similar problem for steel billets and conveyors divided into sections

with various load / unload points.

Conveyors are equipped with through-beam sensors and

1. Assume one bag on the conveyors (if more than one You will need bool indicators for every position)

2. Each position is defined as a sector between the light gates. Integer value points to position

3. You should have LAST KNOWN DIRECTION signal (to react on light gate when conveyor is stopping

i.e. ramping to standstill) - this could be bool (for examople 1=fwd, 0=rev)

4. position is changed on raising edge of the light gate (bag passed light gate) when

- movement is forward and bag was on position before light gate

- movement is reverse and bag was on position after light gate

- alarm if light gate triggered and none of the above occurs

Program:

interlocks: drives ok, any other machines allow movement (i.e. no risk of mechanical clash, etc.,

safety devices i.e. fences ok, etc.)

1. load conveyor and set target position

2. move fwd when interlock met and position<target

3. move rev when interlock met and position>target

4. timers - delay ramp down to position bag on unload position

5. sections - when moving forward give start for occupied section and next one

for reverse give start to occupied section and previous one

Attached: sketch with explanation how to do for assumption that there is one bag on the conveyors.

This can be done without sequencer - arithmetic operations and timers for delayed slow down.

Good luck

Piotr

Piotr thank's, this is great solution...

I have no need to go reverse. Just to move bag to one place forward and then stop.

Also there can be situation like bag on first conveyor and bag on third conveyor.

I need to move both bags for one place.

My second solution will be to turn on all conveyors.

When bag from first conveyor (LG1) comes to second LG2, I will turn off first end second conveyor.

When bag from third LG3 comes to LG4 I will turn off third and fourth conveyor.

For all conveyors i think to provide total working time. After that time turn off all conveyors.

I this situation, after this time I will turn off only conveyor 5.

Anyway you give me good idea.

Hi there.

May I add some of my brainstorming?

My take on the problem is maybe a little different. I think of the conveyor segments as self containing units, that is influenced from the outside (field / user / other units). It is the idea of divide-and-conquer, with the advantage of being portable to other conveying / transporting applications.

It is possible to create an general purpose FB that contains the control of one unit. The FB can then be called several times (linked to individual DBs) for as many as needed. That means if a conveyor is added, one more FB is added.

Cautionary notes..
* It is best to use software timers in the FB.
* Entry and exit coding is required for the first and last conveyor.
* The attached image only represent a simplified design.

Applications where this idea already is functional includes..
* box transporting
* pallet transporting

A portion of the mind-map is included as attached picture.

Thanks for "listening".
w

Hi

How do You decide when load new bag onto the conveyor?

What could be done:

1. loading is permitted when first section is empty

2. we could use independent counters on every section i.e. each sector has a int variable

which is incremented when bag enters the section and decremented when bag leaves the section

3. unload decrement last section

4. FORWARD moves section with bag on it and next section

CODE

1. variables

Bags: ARRAY[1..5] of Int; // Number of bags on each section

Start_Cmd: ARRAY[1..5] of Bool; // Start Commands for all motors

Bag_Loaded : Bool; // External Bag Loaded Indication

Bag_Load_I : Bool; // Bag Load Interlock

LGx : Bool; // Light Gates for each Section

Start : Bool; // External Conveyor START Command

2. Number of Bags on Section 1

    // Load a Bag

    IF (Raising_Edge(Bag_Loaded) THEN Bags[1]:=Bags[1]+1; END_IF;

    // Transfer Section1 --> Section 2

   IF (Raising_Edge(LG1) AND Bags[1]>0) THEN

      Bags[1]:=Bags[1]-1;

      Bags[2]:=Bags[2]+1;

   END_IF;

    // Transfer Section2 --> Section 3

   IF (Raising_Edge(LG2) AND Bags[2]>0) THEN

      Bags[2]:=Bags[2]-1;

      Bags[3]:=Bags[3]+1;

   END_IF;

    // Transfer Section3 --> Section 4

   IF (Raising_Edge(LG3) AND Bags[3]>0) THEN

      Bags[3]:=Bags[3]-1;

      Bags[4]:=Bags[4]+1;

   END_IF;

    // Transfer Section4 --> Section 5

   IF (Raising_Edge(LG4) AND Bags[4]>0) THEN

      Bags[4]:=Bags[4]-1;

      Bags[5]:=Bags[5]+1;

   END_IF;

    // Transfer Section5 --> UNLOAD

   IF (Raising_Edge(LG5) AND Bags[5]>0) THEN

      Bags[3]:=Bags[5]-1;

      Bags_Unloaded:=1; // this must be cleared by bag receiving machine once acknowledged

   END_IF;

// Total Bas on Conveyor

Bags:=Bags[1]+Bags[2]+Bags[3]+Bags[4]+Bags[5];

// Section 1 Control - section with bag AND Next one Starts

Start_Cmd[1]:=START AND Bags[1]<>0;

Start_Cmd[2]:=START AND (Bags[1]<>0 OR Bags[2]<>0);

Start_Cmd[3]:=START AND (Bags[2]<>0 OR Bags[3]<>0);

Start_Cmd[4]:=START AND (Bags[3]<>0 OR Bags[4]<>0);

Start_Cmd[5]:=START AND (Bags[4]<>0 OR Bags[5]<>0);

This will work even if 2 or more bags are on any section at any time.

Bags Load Interlock - You must ensure loading area is clear.

This can be done by a diagonal sensor, additional light gate or allow one bag at section 1

(do not load when Bags[1]<>0)