0 1 00:00:21,520 --> 00:00:22,100 Hello. 1 2 00:00:22,140 --> 00:00:26,910 In this video we are going to learn the importance of scanning order in plc programs. 2 3 00:00:26,910 --> 00:00:28,290 Sample application. 3 4 00:00:28,290 --> 00:00:32,630 The conveyor will move with the start signal but with the stop signal. 4 5 00:00:32,640 --> 00:00:36,000 conveyor movement will be stopped at any time. 5 6 00:00:36,000 --> 00:00:42,210 The number of boxes passing over the belt with the sensor on the converter will be counted when the number 6 7 00:00:42,210 --> 00:00:43,800 of boxes reaches 10. 7 8 00:00:43,800 --> 00:00:45,460 This is an example number. 8 9 00:00:45,630 --> 00:00:50,340 The conveyor will stop and the counter value will be reset for the next count. 9 10 00:00:50,370 --> 00:00:56,580 The above mentioned process will repeat periodically with each start signal. 10 11 00:00:56,580 --> 00:01:01,860 This is the condition , write the plc program according to the above scenario and the test operation 11 12 00:01:01,860 --> 00:01:04,190 in simulator mode. 12 13 00:01:04,200 --> 00:01:08,450 This is the first example solution. 13 14 00:01:08,580 --> 00:01:13,640 And just for this page just you need to know this. 14 15 00:01:13,680 --> 00:01:20,220 Imagine we are using reset command at the third line in here. 15 16 00:01:20,220 --> 00:01:26,680 Here the second example of solution and in here you need to reset command. 16 17 00:01:26,700 --> 00:01:29,190 What happens if we use it in the second line. 17 18 00:01:29,490 --> 00:01:35,070 So let's go to a ISPSoft and let's create a new project and let's take a look. 18 19 00:01:35,070 --> 00:01:35,850 What will happen 19 20 00:01:41,270 --> 00:01:46,580 program section and the new program and say okay a new project. 20 21 00:01:46,580 --> 00:01:58,840 Pages opened I will use m internal relays for example X0 will be m0, X1 will be M1 and X2 21 22 00:01:58,900 --> 00:02:06,010 will be m2 , because of simulator can not detect physical input sometimes. 22 23 00:02:06,010 --> 00:02:14,800 Already we know in here we have set MPU X on and off ,so we can adopt/monitor our physical input on and 23 24 00:02:14,800 --> 00:02:18,580 off but I will use m internal relays. 24 25 00:02:18,640 --> 00:02:22,760 So let us start to write code. 25 26 00:02:23,560 --> 00:02:33,570 LD M0 and LDI M1 and LDI C0 26 27 00:02:33,570 --> 00:02:36,270 and out Y0. 27 28 00:02:36,270 --> 00:02:46,800 I will put OR contact then I will latch output like this and one more network the first showing our example 28 29 00:02:47,160 --> 00:03:00,000 I will use it LD M2 and LD Y0 and CNT C0 3 and I will say just 3 is enough for a moment 29 30 00:03:00,090 --> 00:03:03,280 not 10 in here. 30 31 00:03:03,450 --> 00:03:07,740 LD C0 and reset 31 32 00:03:11,160 --> 00:03:15,850 like this and let's send this project to plc. 32 33 00:03:19,830 --> 00:03:22,620 I will use simulator for a moment. 33 34 00:03:22,620 --> 00:03:29,400 So it is writing this project to the simulator now and simulated a stop situation. 34 35 00:03:29,460 --> 00:03:32,200 I will say run Plc , also confirm. 35 36 00:03:32,220 --> 00:03:35,430 So now we are at run situation. 36 37 00:03:35,430 --> 00:03:45,000 So start signals came and somebody released start button of conveyor and it is turning forward and the sensor 37 38 00:03:45,030 --> 00:03:55,840 detected boxes and counter value is one and the second one and the third one. 38 39 00:03:55,840 --> 00:04:13,200 So what will happen now counter is resetted in here and because of this C0 is didn't lose condition 39 40 00:04:13,740 --> 00:04:16,290 and the latched is not broken. 40 41 00:04:16,560 --> 00:04:25,080 So conveyor is still turning forward and the counter is resetted and we don't need to press the start button 41 42 00:04:25,440 --> 00:04:26,700 anymore, 42 43 00:04:27,030 --> 00:04:27,840 Again I will show you. 43 44 00:04:27,840 --> 00:04:36,290 Set on set off and set on and set off and set on and set off. 44 45 00:04:36,450 --> 00:04:46,470 Still our conveyor is turning forward and forward because when the counter is get to reach three I mean 45 46 00:04:46,470 --> 00:04:48,790 counter goes from off to on. 46 47 00:04:49,020 --> 00:04:55,530 Then suddenly in the next network it is resetting so it's going to beginning position and everything 47 48 00:04:55,530 --> 00:05:02,240 is continue and the counter is already resetted at the second line or second network. 48 49 00:05:02,490 --> 00:05:11,390 So what will happen if I change this network two to network three, I will go off line and I will delete 49 50 00:05:11,510 --> 00:05:27,050 this line and I will edit to here , LD C0 and reset C0 and I will do a download again and it 50 51 00:05:27,050 --> 00:05:28,310 is transferring now 51 52 00:05:34,480 --> 00:05:38,570 object code is sended and I will say yes. 52 53 00:05:38,800 --> 00:05:39,760 Now we are ready. 53 54 00:05:39,850 --> 00:05:45,100 I will go online to my simulator and I will give a start to my conveyor. 54 55 00:05:45,190 --> 00:05:54,130 Now it started and released start button and now conveyor is turning forward and sensor is detected a 55 56 00:05:54,130 --> 00:05:59,340 box and counter value is 1 and counter value will be 2. 56 57 00:05:59,980 --> 00:06:05,280 And what will happen if counter detected or sensor is detected. 57 58 00:06:05,280 --> 00:06:11,620 The third box let's see set on you see when counter-revolution. 58 59 00:06:11,680 --> 00:06:21,730 It equals to tree it will go to up and that moment because of C0 counter zero goes from off to on 59 60 00:06:22,030 --> 00:06:24,430 this contact goes off. 60 61 00:06:24,730 --> 00:06:26,710 Because of this is normally close contact. 61 62 00:06:26,950 --> 00:06:31,210 So the latched is from here is broken. 62 63 00:06:31,210 --> 00:06:43,650 The line broken or it didn't float continuously because of this , this line is now output our conveyor is 63 64 00:06:43,640 --> 00:06:44,380 stopped. 64 65 00:06:44,460 --> 00:06:53,280 And then suddenly we goes to network 2, in the network 2 it was 3 ,but suddenly it resetted and 65 66 00:06:53,280 --> 00:06:54,720 it goes to zero. 66 67 00:06:55,080 --> 00:06:57,430 So what will happen now. 67 68 00:06:57,480 --> 00:07:07,320 Somebody needs to press Start button again and stopped , started and somebody released his hand from the 68 69 00:07:07,320 --> 00:07:08,010 start button. 69 70 00:07:08,010 --> 00:07:13,690 Now conveyor turning again and again and sensor detect box , 70 71 00:07:13,860 --> 00:07:16,410 And the second box it's detected. 71 72 00:07:16,410 --> 00:07:22,740 And the third box detected and suddenly we have no output and conveyor is stopped. 72 73 00:07:22,950 --> 00:07:32,910 So according to our scenario this will repeat periodically with the each start signal so we can say 73 74 00:07:33,360 --> 00:07:34,650 this is the correct one. 74 75 00:07:34,980 --> 00:07:44,700 So the importance of the scanning if you put your reset after counter and if you put your reset before 75 76 00:07:44,700 --> 00:07:46,560 counter what's changing. 76 77 00:07:46,560 --> 00:07:52,740 One time the conveyor stopping , another time continuously conveyor turning. 77 78 00:07:52,830 --> 00:07:54,890 This is really important. 78 79 00:07:55,020 --> 00:07:59,670 Just one network a above or just one network is lower. 79 80 00:07:59,670 --> 00:08:01,550 Everything can be change. 80 81 00:08:01,560 --> 00:08:07,590 So while you are writing plc code code as ladder logic inside of the Delta plc or another one plc 81 82 00:08:07,590 --> 00:08:15,760 you must be careful about the scanning order that all saw in this video. 82 83 00:08:15,810 --> 00:08:16,920 I am finished here. 83 84 00:08:16,920 --> 00:08:18,300 See you in the next video.