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Description
A brief hardware overview of the Allen-Bradley Micro820 PLC (catalog number 2080-L20-20QWB)
Transcript
(00:02) let’s look at the micro 800 PLC and that’s the hardware of that PLC line from Alan Bradley this is a picture of the micro H20 plcs that we will use in the lab and it’s a good representation of the pieces that you would use in a micro 820 application to the far left is our power supply that is basically taking in 120 volt AC power from the wall outlet and converting that to 24 volt DC which is what the microwave 20 PLC requires 24 volt DC to power it as you can see the micro a20 PLC is what we call is a micro PLC so it’s small it
(00:45) did rail mounts there are a fixed amount of embedded i o points meaning that there are so many inputs and so many outputs that are embedded in the controller and that’s what’s available in these green terminal strips that are on the top and bottom and then we have two places here for plugins to expand our i o capability the other thing of node is the kind of the the front of the PLC itself the uh the display panel should always say that has some various indicating LEDs and LEDs that’ll light up based on if one of
(01:25) the inputs are turned on or if one of the outputs are turned on the other thing I noticed the uh the logo just to see that it is uh Allen Bradley product it does provide us the model which is the a20 and it actually gives us the full catalog number of this particular model there are quite a few options when you select the micro H20 PLC based on a few a few variations but this particular model is the 2080-lc20-20 qwb the the numbers here in the middle lc20 just indicate that this is the 820 family the other thing of note on the label is
(02:07) actually the MAC address so this yellow cord coming in on the bottom is actually an ethernet cord plug it into the RJ45 Port that is that’s sitting here kind of underneath so the product has the label for the MAC address every device every ethernet device has a unique Mac address this is different from the IP address that we will later set in the controller but for a quick reference the MAC address is given right here on the label for us to reference the various wires going uh from the from the power supply to this thermal block
(02:47) on the side and then in turn to the to the controller is simply the 24 volt DC so the red wire is the positive 24 volt the black wire is the negative 24 volt so we’ll bring out a a positive n minus 24 volt DC to kind of make the complete circuit power goes out of the power supply through the tunnel block and into the plc here’s another look at the micro H20 with the plug-in module covers removed so we take the two covers off and we can see they’re just basically a socket here that when we place our uh our actual
(03:30) plug-in that would actually be in another input or output card will interface to the to the controller through these sockets so the H20 allows for two plugins if you’re not using the plug-in then the cover that we saw in the previous picture would just remain on here and keep these sockets covered to keep the dust out I should note that the the the displays the LEDs that we didn’t discuss back here are just some indicating LEDs that will give you the status of the micro 820 PLC itself so the lights the chart over here refers to the lights over here
(04:11) so on the left hand side we have run force and ethernet and then on the right hand side we have fault Communications are com and SD for secure digital because there is a secure digital slot in this PLC as well so the green light being on in the case that this PLC is in the Run mode and that we have an ethernet connection if we had a force i o point we would have a light here letting us know that something’s been forced on or forced off if we had a fault we would have a light here any kind of communications that
(04:48) were occurring we would probably see this light flickering and then if there is any kind of secure digital communication going on we would have that light here flickering to a cycling so the next piece of the PLC is just understanding the wiring and where you know where we would bring our inputs and our outputs so this is kind of looking at the top of the PLC so we have a green row of terminals here this is a removable Turner block meaning that we can actually take this green strip completely off of the base unit and put
(05:21) it back on and the top row of the plc is our inputs it just so happens that all of our inputs are on the top row so we have the ability to bring in discrete inputs as well as four analog inputs in this microwave 20 unit so discrete input being simply an on off type input it’s either on or it’s off it’s either a zero or a one or an analog input which would have an actual value to it in this case the microwave 20 will bring in a voltage signal which would be a 0 to 10 volt signal so that it would receive a signal
(06:05) between 0 and 10 volts and then inside the PLC it would in turn scale that voltage value to to become an actual shall we say engineering unit that you could use in the program and we’ll discuss that as we go into the analog section the other green terminal block here is kind of unique to the micro a20 and this is a Communications serial Communications Port so we have D plus D minus G and RX at TX and a g so the microwave 20 is capable of RS 485 communication as well as rs-430 232 communication so for 485 communication we’ll use the D
(06:51) plus the D minus and the g for ground and for 232 communication we’ll use the RX and the TX and the g r x for receive TX for transmit so when we do configure our microwave 20 if we were going to use the serial port for some sort of communications we need to verify and specify that it is set to either 45 or 232 and then we need to wire to the appropriate Port based on the selection we use then in turn looking at the bottom of the PLC we see another row of green Terminals and this row of terminals is for the discrete outputs and the one
(07:39) analog output it also has the two two terminals here that will be for the power so we have to bring 24 volt DC power to the PLC in order to energize it and make it actually run the rest of these terminals are all dedicated to the outputs from the plc so this V 0-0 or I should say v o dash zero they’re very the O’s and the zeros look very similar as each other of course so this is vo for voltage out Dash zero for zero referring to the first output we we uh we reference from zero as our first output so this is our voltage output
(08:24) and then over here we have just an o 0 0 0 1 0 2 0 3 Etc these are discrete outputs so over output 0 for the first one for the second two for the third output fourth fifth sixth seventh output so the microwave 20 that we’ll have in the lab will be pre-wired and you’ll be able to take it and just uh plug in an ethernet cord to it and be able to connect to it and and program it and download to it and and test it out but just to get familiar what what the pieces of the micro PLC it’s quite simple [Music] um pretty much has everything built into it
(09:18) and it does have the ability to add a few expansion i o cards whereas we’ll get our larger PLC platforms such as the control objects that we also have in our lab those are going to be more of a we have to kind of specify and build up the rack so it doesn’t come kind of pre you know pre-built and like the micros do you have to specify I want this type of CPU I want these I O cards and you need these communication cards and then you will put them insert them in the chassis so you have to buy all the pieces loose shall we say and then kind of put
(09:56) them together the advantage of the of that is of course you have a lot of flexibility in choosing uh what you need for your application whereas in these micro plcs if you don’t have that much flexibility in what you can do you have what’s built into the base unit and you have whatever expansion i o capabilities that are available to you sets it that kind of concludes our introduction to the hardware in our next video we’ll start to look at more about the wiring of the inputs and the outputs that would happen on those green turtle
(10:35) strips
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