Wire Analog 4-20mA to 0-10VDC inputs of Micro820 PLC and scale

I'd assist them today we're gonna continue on with our last video where we were talking about wiring analog signals to now and bradley micro 820 plc please take a moment to like this video and subscribe to our channel we put out at least one automation video we also feel free to ask any questions in the comments your question this week could easily be next week's automation topic by the end of the last video we had wired analog voltage inputs and outputs to our allen-bradley micro 820 PLC however most of your analog signals in industrial environments are going to be 4 to 20 mili-amp signals so today we're going to go through how you can wire those to the voltage inputs that are on the base of your micro 820 PLC for this video we're going to be using one of our PLC trainers we'll also be using the PLC tools SIMD I say LP - this is the analog simulator that can simulate both a voltage and a milliamp signal we're gonna add a few terminal blocks just to give us a place to win some water and we're gonna need a 250 ohm resistor let's go ahead and snap our two extra terminal blocks on our trainer and then we'll just leave our potentiometer wire to end put 0 we're gonna wire this to input 1 first let's take our resistor and put it across these two terminals our resistor has the two leads coming off of it just bend them around and pop 1 into 1 and the other into the other and then along with that on the same side squeeze a wire beside each side of that resistor and then the wire on the left go ahead and connect it to I - 0 1 or input 1 on the top of your PLC it's a 4 terminal from the left and the wire on the right terminal connect it to the - of our DC power supply and what we've done is we've actually added an additional load into the circuit and using this Ohm's law pie chart which open the way - in the description we can calculate the milliamps that are going through this based off of our mr. value and the voltage that were measuring here and this really is not some homemade way to measure a million value this is truly how most PLC's measured is they'll have a load resistor measure the voltage and then they're scaling it so let's go ahead add a 1 to each of the other side of these two terminals that we've added so we can connect our analog simulator to it and the left one that's going to our analog input we're gonna put on our red post and the right one which is going to the common of our DC power supply we're going to put on our black post and then let's go back into our program from our voltage exercise which was just a basic move statement and let's change this analog input zero to analog input one where we just connected that wire and in most downloaded and if you need help downloading we have a video on it and I'll put a link this whole series in the description now let's go to current source mode and let's start bringing the analog signal up so at one milliamp we're at roughly a hundred units on our analog signal there you go on up let's say - for the lamp we're at roughly 4 now guys this is a pure coincidence and we'll go through the scaling of this and a little bit let's just take that on up to 20 milliamp [Music] and now we're at roughly 2,000 units so to make it a little easier to understand what these units are that we're seeing here let's modify our wiring from our last one last time we had our digital voltage gauge going to output zeros let's take it off for now and connect it also to this left terminal here that way we can read the voltage that we're measuring along with that milliamp signal so let's flip our trailer around so now as we run our milliamp signal up and down our voltage is changing as well and so if we take this down to four milliamp we're showing one volt now using this Ohm's law pie chart we know our load resistor is 250 ohm and we know that we're putting out 4 million but we won't voltage then we will take our amperage and multiply it by our owns now that's milliamps so it would be 4 milliamp not 4 amps times our 250 ohms and that is going to give us 1 volt so we take it up to 8 then we're showing 2 volt here so if we go back to our homes law formula then 8 milliamps times our 250 ohm resistor is going to be 2 volts and you can go through it and like here's a chart showing you all of them and yes 1 volt through 5 volt is gonna be 4 milliamp through 20 milliamps so now let's scale this value in our PLC so we were using a basic move instruction before so the first thing we need to go is what is the scale of this 0 to 10 volt signal well it is 0 to 4095 units so what we can do that with that is we can use the scale instruction and put this in to our milliamp values so just double click up here where it says mooo that's gonna bring up your instruction box selector and just start typing scale and there it is the scaler bring it in and right away we have a warning right here on our analog input if you go to that bottom left corner where you see that little warning icon it says mismatch between the assigned expression resulting type word and the target real what that means is everything on this one requires a real number and this right here is a word well they have a greater destruction to fix that so let's just click our instruction block and drag it down and if we just start typing any then this any instruction will convert anything that you have to anything that you need so right here we have any two real well click it click OK and now we'll take that analog input and put it on the input of that any two real instruction and then here we're just going to create we'll call this our analog for all real and that will be a real and then we're gonna take that same value and put it right into that scaler so that because that now we have our minimum input and our maximum input that we need to figure out and at least when you first think about it it would be zero which by the way in this if you just put the zero you're gonna get that same error because it's gonna cheat that as a long integer you need to put zero point zero and that'll make it be a real and you would think you would just go to 4 0 9 5 but the issue is that is for a 0 to 10 volt sooner our milliamps are from that one volt to 5 volt so we either need to know that full analog range or we're gonna have to do some math here and let's go ahead and do the math let's just go here to our calculator and we know that 4 0 9 5 is 10 volt but a maximum of our log signal is 5 volts so if we take that 4 0 9 5 and divide it by 2 that's gonna be our 5 volt value so 2040 seven and a half so let's take that and put that there to zero for 7.5 then we need to figure out the 1 volt signal well this is 5 volts the 1 volt is gonna be this number divided by 5 so divided by 5 that's gonna put us at 4 0 9 and 1/2 so that is going to be our input minimum or 0 9.5 so then our output minimum is gonna be 4 point 0 and our output max is going to be 20 point 0 and then instead of going to our analog signal we're just going to look at this one in the program so let's create a tag and we will just call it analog milliamp scale and that will be a real and let's go ahead and download this program so we're showing 8 milliamp on our analog signal and we're right at about 8 million on our scale value so if we bring it down to 4 milli amp we're showing four milliamp and if we bring it up to 20 and we're showing right at 20 million so there's how you connect a milliamp signal to your voltage input on the base unit of a micro 820 PLC now there is one other problem that we're going to tackle in the next video is the range of my output here is 4 to 20 mili-amp and in many applications you need to stay within that range but our analog simulator can actually go to 22 million and if we take it to 22 milli amp then well we're letting a little analog range here but we're showing 21 and 1/2 and likewise if we bring it down to 2 milliamps then it's showing two milliampere on our scale value so we can go out of the range and this can become a big issue on say an analog output or integral wind-up on a PID so in our next video we're actually going to create a user-defined function block that can be used throughout your program to prevent these signals from going out of their ranges till next time hi this is Dylan and this is neighbor of TW controls we run the automation store hey thanks for finding our channel here's a playlist with some similar videos and YouTube thinks you like this video please like our video and subscribe to our Channel and if our videos have helped to make some money and you're not using our products please consider supporting us on patreon till next time see ya

Channel: Tim Wilborne

Views: 11,337

Keywords: micro820 4-20ma, micro820 analog input, analog sensor, analog input, wiring inputs, Tim Wilborne, 4 to 20 milliamp signal, pid controller, connected components workbench, micro800 controllers, analog signal, connected components workbench tutorial, connected components workbench programming, analog signal generator, allen bradley plc training, 4-20ma current loop, 4-20ma signal generator, 4-20ma explained, 4-20 ma conversion formula, 4-20ma loop, 4-20 ma calculation

Id: tZtBSUYUcfk

Length: 11min 9sec (669 seconds)

Published: Wed Apr 29 2020