Can a HMI control VFD without a PLC ?

[aec]

OK but not ok

hi sorry for the delay .
After going through their manual have some what gained knowledge .
And yes we can control unidrive with this HMI .
Using this HMI I would be connecting to unidrive sp one HMI will be connected to four unidrives through rj45 cable and switch . What I'am supposed to do is to program the HMI in such a way that the operate when selects Unidrive-1 then it should display a page with 6 different RPMS , again from it the operator will select the required rpm in which he wants the pump to run . Now I am learning how to assign tags which is new to me (being fresh ) then how to alot different rpm's and how to send signal or to set the rpm to the unidrive .
Also I have doubt whether we can assign 6 different speed with singal UNI DRIVE ???
how to fix the rpm??? like 100,200,300,400,500,600 to each button ???

If anybody have worked before with this Hmi or have worked with similar software please help me to understand how it works .

 

[aec]

Hi all,

I have learnt how to program the tags and how to write various speed .

I need to know how to assign rpm ??? on what basis ????
Like 100 , 200 , 300 .

My boss says it is based upon the frequency . How will I know for which frequency what rpm will match ??????

awaiting your advice

 

[alan_505]

Set up a spreadsheet in Excel and create a column from 0 to 50hz then create a colum beside that with the motor maximum rpm at motor freq at the motor freq and then us fill to get rpm versus freq.

Alan

 

[Clay B.]

Hi all,

I have learnt how to program the tags and how to write various speed .

I need to know how to assign rpm ??? on what basis ????
Like 100 , 200 , 300 .

My boss says it is based upon the frequency . How will I know for which frequency what rpm will match ??????

awaiting your advice

Look at this as a scaling function. You need a certain RPM. This RPM thru SCALING will represent a frequency. It is the same as if you where creating an Anlog Output based on data inside of a PLC. What you need to figure out is the Ratio between Frequency and RPM. It may not be liniar but it should be pretty close.

 

[aec]

Set up a spreadsheet in Excel and create a column from 0 to 50hz then create a colum beside that with the motor maximum rpm at motor freq at the motor freq and then us fill to get rpm versus freq.

Alan

Thanks alot alan I will follow this


Sorry if this sounds too basic

RPM is it same for all the pumps or will it differ . If yes then will the pump vendor have the RPM of that concern pump printed in its data sheet ????

"Look at this as a scaling function. You need a certain RPM. This RPM thru SCALING will represent a frequency. It is the same as if you where creating an Anlog Output based on data inside of a PLC. What you need to figure out is the Ratio between Frequency and RPM. It may not be liniar but it should be pretty close."

Have never worked with analog signal before as this is my second project thats why trying to learn:book: .

When I asked my boss he said they will provide us the detail of RPM (I dont know who ) but until then I want to know how it is done .

I thank god for this website where I'am learning many things interms of practical experience .Eager to learn more . thanks in advance :site:

 

[Clay B.]

Scaling Basics

Scaling is taking data in one form and converting it into another. THe most common in PLC is taking raw data from a analog input signal and converting it into engineering units.

Example: (I am taking liberal use of my numbers to keep the math simple)

I have a pressure sensor that measures from 0 to 100 PSI. The analog signal is 0 vdc at 0 PSI and 10 VDC at 100 PSI. OK inside my PLC I see 1000 in my analog input register when the pressure is 0 PSI and I see 10000 in my register at 100 PSI. Now looking at those numbers you could guess what the Analog input value would be 5000 at 50 PSI. But you need to display this on a screen so you look for the ratio. In my super easy example the ratio is 100 to 1. So to create my scaled display I would take the analog input and divide by 100 and I would have my display. So when my analog output read 2500 my display would read 25.

That is the extreme basics of scaling

In your case you need to find the ratio between Hertz and RPM. You can use a lookup table as described but what happens when you want to create a throttle. As in when asked for a RPM in between 2 you have setup. Also if your drive is not setup in speed mode then your actual RPMs will vary based on load.


Hope this helps.
Clay

 

[aec]

Thanks clayB it is really a good explanation .Thank you very much .

I will update the post as and when I get more information .

 

[Clay B.]

Cool. I have controled several drives from a Red Lion G3 over ModbusRTU. I had a problem with Comm faults (drive side issue) and dropped the experiment. It worked but did not work well so I know its possible but be prepared for some hard lessons.

Biggest issue with projects like this tends (for me anyway) tends to be the Comms.

Start with one drive and get it working the way you want then add the next, get it working etc...

As my old boss and one of my best mentors said "It is always better to walk slowly forward than to run back and forth. Both methods will get you to the same place at about the same time but the slow and steady gets you there with more hair still on your head and less heartburn."

He also said a healthy appetite for booze will lenghten your career. Man was genious.

 

[ndzied1]

Please Consider Safety In Whatever Solution you Choose

Please make sure you have a way to stop the motors besides the commands from the HMI. At a minimum you should have an E-Stop in the system to drop power to the drives if all else fails.

 

[aec]

"Start with one drive and get it working the way you want then add the next, get it working etc..."

sure I will start with one drive and follow step by step proceedure so that it will be easy for me to note the mistakes and correct it:nodi:

"Please make sure you have a way to stop the motors besides the commands from the HMI. At a minimum you should have an E-Stop in the system to drop power to the drives if all else fails."

sure we will have a e-stop :nodi:

And by the way my boss told we will be receiving the products by the end of this month until then I will be reading their manual and will try to learn something in advance .And will update my doubts for your advices .
:site:

 

[aec]

Hi ,

Thank you all for your support now I am able to connect and control the uni-drive’s with HMI through Ethernet TCP/IP .
It is working fine .Totally I am having seven VFD’s and Two HMI. I am controlling the start/stop and speed of the pump.

And I am using the same Drives and HMI which I have mentioned in my earlier post

Thank you all for your support . :site::site: