Conveyor Control - PLCS.net

Robocoaster · May 21st, 2022, 02:07 PM

Hi everyone, I'm newbie at here.I need to help.Can you share your experience to me?
The scheme is as at picture.

The robot is palletizing at conveyor 1 and then send to me palletcompletedbit. After, ı must move this pallet to conveyor 2 with plc code. Also my customer want to run conveyors manually via buttons.

My code is :

[/ladder][/code]
timer_conv2empty(in:=,pt:=t#20s);

CASE MachineMode OF
Man:
StateAuto:=0;
StateConv1:=0;
StateConv2:=0;

IF AlarmStatus THEN
StateMan:=99;
END_IF
IF StateMan=0 AND bttnMode_RTRIG.Q THEN
MachineMode:=Auto;
END_IF

CASE StateMan OF
0: (*Manual control*)
IF bttnConveyor1 THEN
IF NOT in_Sensor1 THEN
out_Conveyor1:=TRUE;
ELSE
out_Conveyor1:=FALSE;
END_IF
END_IF

IF bttnConveyor2 THEN
IF NOT in_Sensor2 THEN
out_Conveyor2:=TRUE;
ELSE
out_Conveyor2:=FALSE;
END_IF
END_IF

IF bttnConveyorTransfer THEN
IF NOT in_Sensor2 THEN
out_Conveyor1:=TRUE;
out_Conveyor2:=TRUE;
ELSE
out_Conveyor1:=FALSE;
out_Conveyor2:=FALSE;
END_IF
END_IF

IF NOT bttnConveyor1 AND NOT bttnConveyorTransfer THEN
out_Conveyor1:=FALSE;
END_IF

IF NOT bttnConveyor2 AND NOT bttnConveyorTransfer THEN
out_Conveyor2:=FALSE;
END_IF
99: (*Alarm*)
out_Conveyor1:=FALSE;
out_Conveyor2:=FALSE;
IF NOT AlarmStatus THEN
StateMan:=0;
END_IF
END_IF
END_CASE;
Auto:
StateMan:=0;

IF AlarmStatus THEN
StateMan:=99;
END_IF
IF (StateAuto=0 OR StateAuto=99) AND bttnMode_RTRIG.Q THEN
MachineMode:=Man;
END_IF

CASE StateAuto OF
0: (*Stop*)
out_Conveyor1:=FALSE;
out_Conveyor2:=FALSE;
IF in_StartButton_RTRIG.Q THEN
StateAuto:=1;
END_IF
1: (*Running*)
IF in_StopButton_RTRIG.Q THEN
StateAuto:=0;
END_IF

CASE StateConv1 OF
0: (*initial*)
out_Conveyor1:=FALSE;
IF NOT in_Sensor1 THEN
StateConv1:=1;
ELSE
StateConv1:=2;
END_IF
1: (*conveyor empty*)
IF palletcompletedbit THEN
out_Conveyor1:=TRUE;
ELSE
out_Conveyor1:=FALSE;
END_IF

IF out_Conveyor1 AND in_Sensor1 THEN
StateConv1:=2;
END_IF
2: (*conveyor loaded*)
IF StateConv2=1 THEN
out_Conveyor1:=TRUE;
ELSE
out_Conveyor1:=FALSE;
END_IF

IF NOT in_Sensor1 AND in_Sensor2 THEN
StateConv1:=1;
END_IF
END_CASE;

CASE StateConv2 OF
0: (*initial*)
out_Conveyor2:=FALSE;
IF NOT in_Sensor2 THEN
StateConv2:=1;
ELSE
StateConv2:=2;
END_IF
1: (*conveyor empty*)
IF StateConv2=2 THEN
out_Conveyor2:=TRUE;
ELSE
out_Conveyor2:=FALSE;
END_IF

IF out_Conveyor2 AND in_Sensor2 THEN
StateConv2:=2;
END_IF
2: (*conveyor loaded*)
timer_conv2empty.IN:=NOT in_Sensor2 ;
IF timer_conv2empty.Q THEN
StateConv2:=1;
END_IF
END_CASE;
99: (*Alarm*)
out_Conveyor1:=FALSE;
out_Conveyor2:=FALSE;
IF NOT AlarmStatus THEN
StateAuto:=0;
END_IF
END_CASE;
END_CASE;
[code]
[ladder]
What should I do if the pallet stays between the sensors?
What should I do if the sensors are triggered incorrectly?

thank you for reply

drbitboy · May 21st, 2022, 02:23 PM

Welcome to the forum!

If you put [/ladder] after the code and [ladder] before the code, you can keep the indentation ([/code] and [code] also works but it more limited by width):



 timer_conv2empty(in:=,pt:=t#20s);



    CASE MachineMode OF

    Man:

    StateAuto:=0;

    StateConv1:=0;

    StateConv2:=0;



        IF AlarmStatus THEN

        StateMan:=99;

        END_IF

        IF StateMan=0 AND bttnMode_RTRIG.Q THEN

        MachineMode:=Auto;

        END_IF



        CASE StateMan OF

        0: (*Manual control*)

            IF bttnConveyor1 THEN

                IF NOT in_Sensor1 THEN

                out_Conveyor1:=TRUE;

                ELSE

                out_Conveyor1:=FALSE;

                END_IF

            END_IF



            IF bttnConveyor2 THEN

                IF NOT in_Sensor2 THEN

                out_Conveyor2:=TRUE;

                ELSE

                out_Conveyor2:=FALSE;

                END_IF

            END_IF

            

            IF bttnConveyorTransfer THEN

                IF NOT in_Sensor2 THEN

                out_Conveyor1:=TRUE;

                out_Conveyor2:=TRUE;

                ELSE

                out_Conveyor1:=FALSE;

                out_Conveyor2:=FALSE;

                END_IF

            END_IF

            

            IF NOT bttnConveyor1 AND NOT bttnConveyorTransfer THEN

            out_Conveyor1:=FALSE;

            END_IF



            IF NOT bttnConveyor2 AND NOT bttnConveyorTransfer THEN

            out_Conveyor2:=FALSE;

            END_IF

        99: (*Alarm*)

        out_Conveyor1:=FALSE;

        out_Conveyor2:=FALSE;

            IF NOT AlarmStatus THEN

            StateMan:=0;

            END_IF

        END_IF    

        END_CASE;

    Auto:

    StateMan:=0;



        IF AlarmStatus THEN

        StateMan:=99;

        END_IF

        IF (StateAuto=0 OR StateAuto=99) AND bttnMode_RTRIG.Q THEN

        MachineMode:=Man;

        END_IF



        CASE StateAuto OF

        0: (*Stop*)

        out_Conveyor1:=FALSE;

        out_Conveyor2:=FALSE;

            IF in_StartButton_RTRIG.Q THEN

            StateAuto:=1;

            END_IF

        1: (*Running*)

            IF in_StopButton_RTRIG.Q THEN

            StateAuto:=0;

            END_IF

            

                CASE StateConv1 OF 

                0: (*initial*)

                out_Conveyor1:=FALSE;

                    IF NOT in_Sensor1 THEN

                    StateConv1:=1;

                    ELSE

                    StateConv1:=2;

                    END_IF

                1: (*conveyor empty*)

                  IF palletcompletedbit THEN

                  out_Conveyor1:=TRUE;

                  ELSE

                  out_Conveyor1:=FALSE;

                      END_IF

                

                  IF out_Conveyor1 AND in_Sensor1 THEN

                  StateConv1:=2;

                  END_IF

                2: (*conveyor loaded*)

                  IF StateConv2=1 THEN

                  out_Conveyor1:=TRUE;

                  ELSE

                  out_Conveyor1:=FALSE;

                      END_IF

            

                   IF NOT in_Sensor1 AND in_Sensor2 THEN

                   StateConv1:=1;

                   END_IF

                END_CASE;



                CASE StateConv2 OF 

                0: (*initial*)

                out_Conveyor2:=FALSE;

                    IF NOT in_Sensor2 THEN

                    StateConv2:=1;

                    ELSE

                    StateConv2:=2;

                    END_IF

                1: (*conveyor empty*)

                  IF StateConv2=2 THEN

                  out_Conveyor2:=TRUE;

                  ELSE

                  out_Conveyor2:=FALSE;

                      END_IF

                

                  IF out_Conveyor2 AND in_Sensor2 THEN

                  StateConv2:=2;

                  END_IF

                2: (*conveyor loaded*)

                  timer_conv2empty.IN:=NOT in_Sensor2 ;

                  IF timer_conv2empty.Q THEN

                  StateConv2:=1;

                  END_IF

                END_CASE;

        99: (*Alarm*)

        out_Conveyor1:=FALSE;

        out_Conveyor2:=FALSE;

            IF NOT AlarmStatus THEN

            StateAuto:=0;

            END_IF

        END_CASE;

    END_CASE;

Hellsbishop34 · May 21st, 2022, 10:07 PM

CASE StateConv1 OF 

                0: (*initial*)

                out_Conveyor1:=FALSE;

                    IF NOT in_Sensor1 THEN

                    StateConv1:=1;

                    ELSE

                    StateConv1:=2;

                    END_IF

                1: (*conveyor empty*)

                  IF palletcompletedbit THEN

                  out_Conveyor1:=TRUE;

                  ELSE

                  out_Conveyor1:=FALSE;

                      END_IF

                

                  IF out_Conveyor1 AND in_Sensor1 THEN

                  StateConv1:=2;

                  END_IF

                2: (*conveyor loaded*)

                  IF StateConv2=1 THEN

                  out_Conveyor1:=TRUE;

                  ELSE

                  out_Conveyor1:=FALSE;

                      END_IF

            

                   IF NOT in_Sensor1 AND in_Sensor2 THEN

                   StateConv1:=1;

                   END_IF

                END_CASE;



                CASE StateConv2 OF 

                0: (*initial*)

                out_Conveyor2:=FALSE;

                    IF NOT in_Sensor2 THEN

                    StateConv2:=1;

                    ELSE

                    StateConv2:=2;

                    END_IF

                1: (*conveyor empty*)

                  IF StateConv2=2 THEN

                  out_Conveyor2:=TRUE;

                  ELSE

                  out_Conveyor2:=FALSE;

                      END_IF

                

                  IF out_Conveyor2 AND in_Sensor2 THEN

                  StateConv2:=2;

                  END_IF

                2: (*conveyor loaded*)

                  timer_conv2empty.IN:=NOT in_Sensor2 ;

                  IF timer_conv2empty.Q THEN

                  StateConv2:=1;

                  END_IF

                END_CASE;

*Disclaimer* I did not proof read the code. Quick skim.

Buffer the sensor inputs with Rising and Falling edge triggers. You can use these edges for tracking purposes and proper sequence. Conveyor is loaded on the rising edge of sensor 1. The falling edge would set a "transitioning" state. You can add a timer to this bit to alarm that sensor 2 never saw a transition. If sensor 2 shows a rising edge without a transitioning flag then you have an improper sequence. Assuming I understand your layout correctly.

jstolaruk · May 21st, 2022, 11:47 PM

In my industry, these are commonly called zone conveyors but we try to use (2) sensors per zone, pallet_entering (which you have) and pallet_present. Makes the logic easier for Sparky.

parky · May 23rd, 2022, 05:35 AM

Personally, I would do this in ladder, it's easier the OP did not state what PLC & it seems a little complicated & messy.
Here is one that works (well as I assume what is required), the OP did not state if in manual the operator controls the conveyors ignoring certain things like the sensors or signal from palletiser etc. so assume not, have not included all things like that.
A simple alarm if for example the conveyors run for more time than expected to move pallet from conveyor 1 to conveyor 2 sensor then it assumes stuck pallet regardless of if moved off sensor 1.



PLS(Auto_Man,Auto_Sw_Rising_Pulse);   (* Create a rising pulse on switching to auto *)

PLF(Auto_Man,AUto_Sw_Falling_Pulse); (* Create a falling pulse when switching to Manual*)



IF Auto_Sw_Rising_Pulse OR AUto_Sw_Falling_Pulse THEN  (*Onswitching from Auto to Man or man to Auto stop the conveyors *)

	SEQ:= 0;

	END_IF;

IF  SEQ = 0 AND  Pallet_Comp_Bit AND PE01 AND NOT PE02 AND Auto_Man THEN

	SEQ:= 1;   (* Run Conveyor 1 to Conv 2 iin Auto*)

END_IF;



IF SEQ = 1 AND PE02 THEN  (* When in Auto & pallet reaches PE02 then set SEQ back to 0 *)

	SEQ:= 0;

END_IF;



IF SEQ = 0  AND PE01 AND Start_Button AND NOT PE02 AND NOT Auto_Man THEN

  SEQ:= 11;   (* Run conveyors in man*)

END_IF;



IF PE02 OR Stop_Button  AND SEQ = 11 THEN  (* Stop in Manual if reaches PE02 or Stop pressed *)

	SEQ:=0;

END_IF;



CASE SEQ OF    (* Run the conveyors*)

	0:  Conv_1_Out:= FALSE;

	 Conv_2_Out:= FALSE;

	1: Conv_1_Out:= TRUE;

	 Conv_2_Out:= TRUE;

	10:  Conv_1_Out:= FALSE;

	 Conv_2_Out:= FALSE;

	11: Conv_1_Out:= TRUE;

	 Conv_2_Out:= TRUE;

END_CASE;



(* Alarm handling*)

Alarm_Timer(IN:= (Conv_1_Out OR Conv_2_Out),PT:=T#10s);  (* If conveyors run for more time than expected then set alarm*)

IF Alarm_Timer.Q THEN

	SEQ:= 99;

	Conv_1_Out:=FALSE;

	Conv_2_Out:=FALSE;

END_IF;



IF SEQ = 99 AND Alarm_Reset THEN  (*Alram reset *)

	SEQ:= 0;

END_IF;

Did not add any on/off delay on the photocells, this would depend on if the natural stop of the conveyors ensured the photocells were fully covered or if the pallets would have gaps that the photocells could see.

BachPhi · May 23rd, 2022, 06:45 AM

Yes, the 'real' ladder logic will be shine in this case. I am guessing his homework requirement to be ST.
your logic is a better than the two previous two.
but it wont work because of PE01 need to be broken "IF SEQ = 0 AND Pallet_Comp_Bit AND PE01 AND NOT PE02 AND Auto_Man THEN".

I'd start the seq when receiving the complete bit. run it to PE01, then start Conv2 at that point.

parky · May 23rd, 2022, 07:32 AM

It is assumed that PE01 is made when the pallet is placed on the conveyor this works I have simulated it. It assumes that the pallet is put on the conveyor, the PE is made which tells the palletizer to do what ever it needs to do then the palletizer gives the signal to transfer it. But yes if the PE is not made & only rely on the palletizer to initiate it then it would need to be modified, I realise now that the picture of the two conveyors shows the pallets not on the PE's however, this is wrong as the conveyor 2 PE is not covered which it would have to be to stop the sequence (or rely on timers to assume pallet in middle of conveyor (very poor design if so ).when passed from conveyor 1 to 2, the OP's description is poor in regarding exactly how it should work.

L33er · May 23rd, 2022, 08:17 AM

Are you saying his picture is not clear? lol.

JesperMP · May 23rd, 2022, 09:05 AM

So only one pallet to be present on each conveyor ever ?
Or can one pallet start leaving conveyor 2 when the pallet on conveyor 1 has begun to leave ?
Shall the sensor at the entry of conveyor 2 also function as the exit sensor for conveyor 1 ?
Can the pallet extend from conveyor 2 onto conveyor 1 without conveyour 1 running until the sensor 1 is activated ?
Also, consider error scenarios, such as there is a pallet on conveyor 2, and when it starts to move but no signal from sensor 1 is received, there is possibly a blockage.
Similar, the signal(s) on sensor 1 or sensor 2 stays on and does not go off.
etc..
What shall be the functionality of the buttons ?

Write a detailed spec of the programs functionality, and the actual code almost writes itself.

Robocoaster · May 23rd, 2022, 10:57 AM

Thank you all answers. You have been very helpful.

Robocoaster · May 23rd, 2022, 11:04 AM

Actually, every conveyor have a sensor. I dont want to lose pallet at conveyor. So, ı set persistent that conveyors state. Also, these buttons at HMI.So, I didn't use rising or falling edge.
Is this true ?

parky · May 23rd, 2022, 11:15 AM

@Jesper: My thoughts exactly, I have done many of these & in all cases the sensor is covered when pallet in place, did many systems where the pallets came in different sizes i.e. half euro, full Euro, 1.5 Euro, 2 Euro & if I remember correctly 2.5 Euro sizes, so the last two would straddle 2 of the conveyors. These were feed conveyors to a Strapper a total of 14 & two on the outlet. The pallets were measured in a number of different configurations just before the Strapper, by length, width, if pallet had bottom runners or not (if runners then swords were used to feed the straps or straps were sent between the conveyor rollers) the strapping patterns were determined by the above i.e. could be 3 or 4 straps across, if half Euro then one strap each way, full Euro 2 straps each way so about 30 strap patterns in total.

parky · May 23rd, 2022, 01:36 PM

Based on what I did last time here is a more concise bit of code that does the same job





PLS(Auto_Man,Auto_Sw_Rising_Pulse);   (* Create a rising pulse on switching to auto *)

PLF(Auto_Man,AUto_Sw_Falling_Pulse); (* Create a falling pulse when switching to Manual*)



IF    Pallet_Comp_Bit AND PE01 AND NOT PE02 AND Auto_Man THEN

	Conv_1_Out:= TRUE;   (* Run Conveyor 1 to Conv 2 iin Auto*)

    Conv_2_Out:= TRUE;

END_IF;



IF  PE01 AND Start_Button AND NOT PE02 AND NOT Auto_Man THEN

     Conv_1_Out:= TRUE;   (* Run Conveyor 1 to Conv 2 iin Man*)

     Conv_2_Out:= TRUE;

END_IF;



IF Stop_Button AND NOT Auto_Man OR PE02   THEN  (* Stop in Manual if reaches PE02 or Stop pressed *)

	Conv_1_Out:= FALSE;   (* Stop Conveyor 1 to Conv 2 iin Auto*)

    Conv_2_Out:= FALSE;

    END_IF;



(* Alarm handling*)

Alarm_Timer(IN:= (Conv_1_Out OR Conv_2_Out),PT:=T#10s);  (* If conveyors run for more time than expected then set alarm*)

IF Alarm_Timer.Q THEN

	Alarm_Bit:= TRUE;

	Conv_1_Out:=FALSE;

	Conv_2_Out:=FALSE;

END_IF;



IF  Alarm_Reset THEN  (*Alram reset *)

	Alarm_Bit:= FALSE;

END_IF;

parky · May 23rd, 2022, 02:10 PM

Could have done it in less lines but at my age all those brackets make my brain hurt so here is a ladder one rung, missing are the alarm for jammed pallet & the stop if switched from auto to man or back.
Just goes to show that ST is fine for calcs but for Boolean Lad is faster to code (well in my old brain) & easier to understand.

May 21st, 2022, 11:47 PM	#4
jstolaruk Lifetime Supporting Member Join Date: Dec 2004 Location: Detroit, SE Michigan Posts: 3,781	In my industry, these are commonly called zone conveyors but we try to use (2) sensors per zone, pallet_entering (which you have) and pallet_present. Makes the logic easier for Sparky. __________________ I don't always test my code but when I do, I do it in production.

May 23rd, 2022, 06:45 AM	#6
BachPhi Member Join Date: Dec 2007 Location: Los Alamos Posts: 564	Yes, the 'real' ladder logic will be shine in this case. I am guessing his homework requirement to be ST. your logic is a better than the two previous two. but it wont work because of PE01 need to be broken "IF SEQ = 0 AND Pallet_Comp_Bit AND PE01 AND NOT PE02 AND Auto_Man THEN". I'd start the seq when receiving the complete bit. run it to PE01, then start Conv2 at that point. __________________ ================================================== ==== This is NOT alt.read.my.mind. No such thing is sh^t-for-brains unless you are posting to alt.read.my.mind. Savvy? ================================================== === Last edited by BachPhi; May 23rd, 2022 at 07:22 AM.

May 23rd, 2022, 07:32 AM	#7
parky Member Join Date: Oct 2004 Location: Midlands Posts: 4,029	It is assumed that PE01 is made when the pallet is placed on the conveyor this works I have simulated it. It assumes that the pallet is put on the conveyor, the PE is made which tells the palletizer to do what ever it needs to do then the palletizer gives the signal to transfer it. But yes if the PE is not made & only rely on the palletizer to initiate it then it would need to be modified, I realise now that the picture of the two conveyors shows the pallets not on the PE's however, this is wrong as the conveyor 2 PE is not covered which it would have to be to stop the sequence (or rely on timers to assume pallet in middle of conveyor (very poor design if so ).when passed from conveyor 1 to 2, the OP's description is poor in regarding exactly how it should work. Last edited by parky; May 23rd, 2022 at 07:36 AM.

May 23rd, 2022, 09:05 AM	#9
JesperMP Lifetime Supporting Member + Moderator Join Date: Feb 2003 Location: Copenhagen. Posts: 15,434	So only one pallet to be present on each conveyor ever ? Or can one pallet start leaving conveyor 2 when the pallet on conveyor 1 has begun to leave ? Shall the sensor at the entry of conveyor 2 also function as the exit sensor for conveyor 1 ? Can the pallet extend from conveyor 2 onto conveyor 1 without conveyour 1 running until the sensor 1 is activated ? Also, consider error scenarios, such as there is a pallet on conveyor 2, and when it starts to move but no signal from sensor 1 is received, there is possibly a blockage. Similar, the signal(s) on sensor 1 or sensor 2 stays on and does not go off. etc.. What shall be the functionality of the buttons ? Write a detailed spec of the programs functionality, and the actual code almost writes itself. __________________ Jesper NOTICE: JesperMP can be impolite, has passive-aggressive tendencies and may use sarcasm !

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May 21st, 2022, 02:07 PM	#1
Robocoaster Member Join Date: May 2022 Location: istanbul Posts: 3	Conveyor Control Hi everyone, I'm newbie at here.I need to help.Can you share your experience to me? The scheme is as at picture. The robot is palletizing at conveyor 1 and then send to me palletcompletedbit. After, ı must move this pallet to conveyor 2 with plc code. Also my customer want to run conveyors manually via buttons. My code is : [/ladder][/code] timer_conv2empty(in:=,pt:=t#20s); CASE MachineMode OF Man: StateAuto:=0; StateConv1:=0; StateConv2:=0; IF AlarmStatus THEN StateMan:=99; END_IF IF StateMan=0 AND bttnMode_RTRIG.Q THEN MachineMode:=Auto; END_IF CASE StateMan OF 0: (Manual control) IF bttnConveyor1 THEN IF NOT in_Sensor1 THEN out_Conveyor1:=TRUE; ELSE out_Conveyor1:=FALSE; END_IF END_IF IF bttnConveyor2 THEN IF NOT in_Sensor2 THEN out_Conveyor2:=TRUE; ELSE out_Conveyor2:=FALSE; END_IF END_IF IF bttnConveyorTransfer THEN IF NOT in_Sensor2 THEN out_Conveyor1:=TRUE; out_Conveyor2:=TRUE; ELSE out_Conveyor1:=FALSE; out_Conveyor2:=FALSE; END_IF END_IF IF NOT bttnConveyor1 AND NOT bttnConveyorTransfer THEN out_Conveyor1:=FALSE; END_IF IF NOT bttnConveyor2 AND NOT bttnConveyorTransfer THEN out_Conveyor2:=FALSE; END_IF 99: (Alarm) out_Conveyor1:=FALSE; out_Conveyor2:=FALSE; IF NOT AlarmStatus THEN StateMan:=0; END_IF END_IF END_CASE; Auto: StateMan:=0; IF AlarmStatus THEN StateMan:=99; END_IF IF (StateAuto=0 OR StateAuto=99) AND bttnMode_RTRIG.Q THEN MachineMode:=Man; END_IF CASE StateAuto OF 0: (Stop) out_Conveyor1:=FALSE; out_Conveyor2:=FALSE; IF in_StartButton_RTRIG.Q THEN StateAuto:=1; END_IF 1: (Running) IF in_StopButton_RTRIG.Q THEN StateAuto:=0; END_IF CASE StateConv1 OF 0: (initial) out_Conveyor1:=FALSE; IF NOT in_Sensor1 THEN StateConv1:=1; ELSE StateConv1:=2; END_IF 1: (conveyor empty) IF palletcompletedbit THEN out_Conveyor1:=TRUE; ELSE out_Conveyor1:=FALSE; END_IF IF out_Conveyor1 AND in_Sensor1 THEN StateConv1:=2; END_IF 2: (conveyor loaded) IF StateConv2=1 THEN out_Conveyor1:=TRUE; ELSE out_Conveyor1:=FALSE; END_IF IF NOT in_Sensor1 AND in_Sensor2 THEN StateConv1:=1; END_IF END_CASE; CASE StateConv2 OF 0: (initial) out_Conveyor2:=FALSE; IF NOT in_Sensor2 THEN StateConv2:=1; ELSE StateConv2:=2; END_IF 1: (conveyor empty) IF StateConv2=2 THEN out_Conveyor2:=TRUE; ELSE out_Conveyor2:=FALSE; END_IF IF out_Conveyor2 AND in_Sensor2 THEN StateConv2:=2; END_IF 2: (conveyor loaded) timer_conv2empty.IN:=NOT in_Sensor2 ; IF timer_conv2empty.Q THEN StateConv2:=1; END_IF END_CASE; 99: (Alarm) out_Conveyor1:=FALSE; out_Conveyor2:=FALSE; IF NOT AlarmStatus THEN StateAuto:=0; END_IF END_CASE; END_CASE; [code] [ladder] What should I do if the pallet stays between the sensors? What should I do if the sensors are triggered incorrectly? thank you for reply Last edited by Robocoaster; May 21st, 2022 at 02:26 PM.

May 23rd, 2022, 08:17 AM	#8
L33er Member Join Date: Feb 2021 Location: North Posts: 168	Are you saying his picture is not clear? lol.

May 23rd, 2022, 10:57 AM	#10
Robocoaster Member Join Date: May 2022 Location: istanbul Posts: 3	Thank you all answers. You have been very helpful.

May 23rd, 2022, 11:04 AM	#11
Robocoaster Member Join Date: May 2022 Location: istanbul Posts: 3	Actually, every conveyor have a sensor. I dont want to lose pallet at conveyor. So, ı set persistent that conveyors state. Also, these buttons at HMI.So, I didn't use rising or falling edge. Is this true ?

May 23rd, 2022, 11:15 AM	#12
parky Member Join Date: Oct 2004 Location: Midlands Posts: 4,029	@Jesper: My thoughts exactly, I have done many of these & in all cases the sensor is covered when pallet in place, did many systems where the pallets came in different sizes i.e. half euro, full Euro, 1.5 Euro, 2 Euro & if I remember correctly 2.5 Euro sizes, so the last two would straddle 2 of the conveyors. These were feed conveyors to a Strapper a total of 14 & two on the outlet. The pallets were measured in a number of different configurations just before the Strapper, by length, width, if pallet had bottom runners or not (if runners then swords were used to feed the straps or straps were sent between the conveyor rollers) the strapping patterns were determined by the above i.e. could be 3 or 4 straps across, if half Euro then one strap each way, full Euro 2 straps each way so about 30 strap patterns in total.

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