Hello. 1
In this video we are going to learn. 2
common 3
special contacts, we need to learn this contacts before to write 4
plc programs because we are going to really need these contacts in our plc projects. 5
when plc is run situation. 6
You can see in here M1000 ,1001 1002 1003 auxiliary relays and these contacts are special 7
M contacts are working. 8
But how. 9
M one thousand contact is means a contact constantly on during operation and detection. 10
When plc is in run status m1000 remains M1001 B contact is constantly off during 11
operation and detection. 12
When plc is in run status M1001 remains off M1002 is on during the first scan when the plc starts 13
to run and remains off afterwards, the pulse width is equals to one scan time. 14
So use this contact for all kinds of initial settings like communications settings like before to 15
start up the while starting up project or starting up plc you can use this contact just once to 16
write some variables to your data registers and M1003 is off during the first scan then plc starts to 17
run and remains on afterward and M1003 enables negative direction. 18
So for m1011,12 and 13 and 14 for the time to adapt our time to 19
give a pulses and also activate some contacts always with the sequentially or time by time to activate 20
we can use this contact M1011 is five millisecond on five milliseconds off M1012 50 21
milliseconds on and 50 milliseconds off M1013 500 milliseconds on 500 milliseconds off M1040 in 30 22
seconds on 30 second off. 23
Let's take a look. 24
These M contacts with an example. 25
So let's create a new project and give a name to this project 26
M contacts our controller type is going to be DVP and the plc type can be SS2 a new program. 27
Okay. 28
Cyclic task can be ladder diagram. 29
Okay creat project and let's write ld m1000 and also I want to create an another network. 30
Okay. 31
LD M1001 ,LD M1002 32
LD M1003 33
LD M1011 34
LD M1012 and one more network LD M1013 35
LD M1014 36
So what we are going to expect from these networks M1000 will always on this is put in here to 37
outputs and what will happen let's watch them all. 38
Or let's monitor them all altogether. 39
So I will just give out y0. 40
I will say to set them all and set y1 , set y2 , set y3 41
set y4 42
also I will. 43
I'm not going to use this in here I will say increöemt D0 44
increment D1 we will learn increment or decrement command in the next videos but I 45
will just give an example to in here increment D2 increment D3 and open our simulator and project 46
is going to be compiled and yes transfer our program or project to Plc and now it's transferring and 47
go back to running state and on. 48
So now look M1000 directly set , this is M1002 just giving it just a single positive pulse when 49
the plc is run. 50
Now you can see it is off but output is high and M1003 giving negative pulse at the moment when 51
run is active. 52
So it is always active too and it it's also giving to output to our coil and it is set 53
And look our values it is giving a 10 millisecond clock pulse five milliseconds high five 54
milliseconds of and this is fifty millisecond high and 50 milliseconds of and this is 500 milliseconds 55
on 500 millisecond off and you see this is our value and one minute is 30 second on 30 second off 56
and it is giving a pulse while this value is increasing because 30 second this is activated so it is 57
incrementing always and third second it is incrementing. 58
And now you can see the values are changing and these special contacts are giving an output according 59
to their special settings. 60
And in here you can see it. 61
Y1 is said not set because M1001 is b contact and normally close contact. 62
So let is make this off, set off then this will be always off. 63
It is not possible to get this. 64
Y0 to reset and M1003 65
Get this off but always on. 66
So let's stop our plc. 67
Our plc is stopped and now just look out to y2. 68
I will give to run our plc and first scan it is set ,so we can use M1000,1001,1002,1003 69
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with like this we can just uh follow our schematic also in here plc is at the run state with 71
M1000 is always on ,when plc is off M1000 goes off in this moment when 72
M1000 goes off and M1001goes high or on and M1002 just giving 73
a pulse in here you can see and M1003giving pulse but in the negative direction 74
for the. 75
time bit you can see it in here one square wave goes high and low and again high this 76
complete time is ten millisecond but to go on and to go off this time is ten millisecond divide by two. 77
This is the result of half of M1011 settings and in here you can see it easily one minute 78
then this goes high and goes to high and high and low and low and low and low and high this time just 79
in the middle and this is 30 second this equals thirthy second and thirthy second on and thirthy. 80
Second off so I'm finished in this video and this special and contacts are going to be helpful and we 81
are going to use them all in our projects also then we can we should learn them all. 82
effectively and there is a lot of m contacts and lot of special D registers and the 83
contact types but these are all the basic ones and the important ones. 84
So I'm finished in this video a moment. 85
So see you in the next video.