akashleo

Communication

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I'm working on a system in which powerflex 40 is already communicated with compactlogix L32B. My system is Ml1400 from my system i want to give analog input to drive so it will change cpm(cycle per minute) accordingly. How to do this I have no idea. Can anyone suggest me how to do this.

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So you're taking a PF40 away from the CompactLogix and installing it on a Micro 1400?

If so, your Micro should have a analog output channels on it. You'll want to use either a 0-10VDC or 4-20mA. Wire the analog output on the PLC to the analog input on the drive. You'll program the PF40 to use the analog input as the primary speed reference (parameter 38), set the minimum frequency (parameter 34) to 0Hz, and the max frequency (parameter 35) to 60Hz.To scale the speed in the drive, you'll need to use parameters 110 through 113.

You will then need to write code for the Micro to look at the input condition that causes the drive to speed up and slow down, and adjust the analog output accordingly. 

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Thanks for help sir. I appreciate your help sir 🙏

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Will the CompactLogix still be controlling the PowerFlex drive, or will you be changing all of the control to the CompactLogix ?

Is it using EtherNet/IP, or analog + digital signals, or a Drive Serial Interface (DSI) connection ?

You're probably aware that the MicroLogix cannot perform the same kind of cyclic I/O control over EtherNet/IP that a CompactLogix can.

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Posted (edited)

@Ken Roach  Sir actually I don't want to interfere established system which works on compactlogix. All i want to is give analog signal to drive from my system so perform defined condition.

Sir actually I'm new to all this thing so I'm not aware of cyclic I/O control.

Thanks for your valuable reply, today I got to learn a new concept. Thanks

Edited by akashleo

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@akashleo if you're wanting to alternate a single PowerFlex40's speed control between the existing CopmactLogix and a newly installed Micrologix 1400 (or any other system), you will have to change the value of drive parameter 38 (Speed Reference) any time you want to change form one controller to the other. While some PF drives can have alternate speed reference inputs (usually referred to as "Speed Ref A" and "-B"), that can be switched back and forth with something as simple as a digital input, the PF40 can only have a single speed reference programmed. 

What is the reason you might have this singe drive change speed control from Compact to Micro and back?

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If the CompactLogix is already controlling the speed of the drive, I would consider leaving that alone and setting up a MSG instruction to get info from the MicroLogix to the CompactLogix. The CompactLogix is really way more capable when it comes to controlling a drive than the MicroLogix. Have some logic inside the CompactLogix to select which reference to send to the drive.

I've had weird things happen when switching between speed references, but that may have just been an unreliable installation.

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Thank you sir, I will go with msg instruction

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If you have some free outputs on the drive, you can make a clever speed select with parameter control on a DO wired to a DI to choose a speed select of parameter 38. I’m not completely understanding what needs to be done. An MSG is pretty simple if you’re sending a new reference 

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Posted (edited)

On 4/3/2021 at 7:08 AM, VFD Guy said:

If you have some free outputs on the drive, you can make a clever speed select with parameter control on a DO wired to a DI to choose a speed select of parameter 38. I’m not completely understanding what needs to be done. An MSG is pretty simple if you’re sending a new reference 

 @VFD Guy My client is using that drive for mould oscillator which is communicated with their own system which comprises of compactlogix plc . I want to run that drive according to my condition which is in between 50-200 cpm but the  difficult part is that if I mess anything with the drive while communicating with ML1400 plc their whole process will stop and i do not have any deep knowledge of drive. I do not want to interfere their system as their is interlocking in their process. Can i  give the final to compactlogix (clinet plc) from my ML1400 through MSG instruction.

note: i want to keep on/off of drive through their plc and only want to change analog value which they give to their drive. 

The speed of drive(cpm in my case will be dyanmic)  their is constant in my program which will multiply with casting speed(analog) and their resultant will be given to drive.

 

Edited by akashleo

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On 3/22/2021 at 9:31 PM, Ken Roach said:

Will the CompactLogix still be controlling the PowerFlex drive, or will you be changing all of the control to the CompactLogix ?

Is it using EtherNet/IP, or analog + digital signals, or a Drive Serial Interface (DSI) connection ?

You're probably aware that the MicroLogix cannot perform the same kind of cyclic I/O control over EtherNet/IP that a CompactLogix can.

 @Ken RoachcompactLogix will control the on/off condition of drive

it is using ethernet/ip

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You will definitely not have success having the CompactLogix and the MicroLogix both communicate with the drive at the same time. That will not work. If you don't want to disturb the CompactLogix system at all, and if it doesn't care about the speed of the drive, it would be simpler to manually change the speed reference source parameter in the drive to point to the analog input and have the MicroLogix drive the analog signal. It may be, though, that the CompactLogix system may also write that source parameter. If you change it and it doesn't stay changed through power cycles of the system, then you'll have to modify the logic inside the CompactLogix and have it use a MSG instruction to read the desired reference from the MicroLogix and pass it on to the CompactLogix.

It's just a thought, but is there any way the CompactLogix could also control the oscillator machine? If a MicroLogix can handle it, it should be very possible to add another program and some Ethernet I/O to the CompactLogix to control it. That way, everything would be in one PLC.

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So reading through the thread again, are these the desired operating conditions?

  • The CompactLogix starts and stops the drive. Never control that from anywhere else.
  • The MicroLogix controls the speed of the drive. Never control that from anywhere else.

If so, this is what I would do:

  • Check to see if the PF drive has been added to Compact's I/O configuration. (If it's currently receiving instruction via Ethernet, I guarantee it has). 
  • Go into that configuration (within the CompactLogix controller, NOT in the drive) and change the speed reference (parameter 38) from "Comm Port" to either "0-10V Input" or "4-20mA Input", whichever you have available on the Micro. This step will ensure that the PF drive is always looking at the analog input for speed reference. It shouldn't care that start/stop and other commands come over eNet. 
  • Hardwire an analog output from the Micro to the appropriate input on the PF drive.
  • Write the code in the Micro to scale and control the analog output for speed. 
  • If you have to make any other adjustments to the PF drive parameters (such as Min/Max frequency, etc) do so in the CompactLogix, not the drive itself. 

This should work for you and minimize system complexity for this unusual control situation you're in. I would also add rung comments in both controllers, and parameter descriptions on the PF (again, within the CompactLogix I/O tree Device Definition) to explain the setup to anyone else working on the system.

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@ElectronGuru the second bullet point would stop the process. It sounds like this isn’t acceptable. Would it be easier to send a reference from the micrologix to the compact logix then do an online edit to redirect the data from the micrologix? 

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@VFD Guy This would have to be done offline and then downloaded, or in the program mode. Of course the process would have to be stopped; about 1/2 the drives out there will not let you change the speed reference while the drive is running. I've never figured out how they go about deciding which drives they'll allow a speed reference change while running, but there it is. There are at least a dozen different ways this can be done. But whichever method is used, I would never want to make a major change like this to a running process. You'd want to have the time to safely and thoroughly test the changes before releasing the process back to production. 

Yes, speed reference data can be sent from the Micro to the Compact but if done over a network, it would almost certainly have to be via a MSG instruction, and that's time and scan consuming. I don't know how responsive the OP's system has to be, but that might make for sluggish performance, depending on how much network traffic they already have. He could also hardwire the analog output from Micro to Compact and go from there, but he stated earlier he wants the analog input direct to the drive from the Micro. 

 

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@ElectronGuru  you’re correct that the speed reference the drive is pointing to probably can’t be changed while the drive is running but by understanding the io image, you can ‘change’ the speed ref on the fly by writing to the logic command to point to a new reference. 
 

I agree that ample testing should be done before changing a live system. Sounds risky in any manner

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If thru EIP, I can always change the speed of the drive.  I prefer not doing the explicit messaging. Rather thru implicit connection with drive.

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