Capturing the motor current from VFD and display in HMI

Hello
I am currently working on to display the motor current information that has to be obtained from ABB VFD (ACS150) in iFix Scada HMI screen. The PLC is Modicon – Quantum and I wrote a program in Unity Pro XL and configured the tag in the HMI but I don’t know how I can input the motor current to PLC I/O or wire to the register. Whether I can use Modbus TCP to read the information from VFD or connect wire to Analog Input. Could some of you please drop a line how to implement in the best way?
Thank you in advance for your time.
Aung

It does not appear that the ACS150 has any provision for communications. The larger drives (ACS550 for example) have a modbus port that allows you to read the drive registers.

Neither appears to be available on the ACS150.

Is there an analog output?
We have often been asked to do torque(current) limiting applications but the current can't be measured by putting a current sensor around the cables between the drive and motor. The current is chopped up and very noises. To get a usable current there must be access to the current used in the model for calculations. Sometimes this can be accessible using an analog output.

Getting the current over a serial port would be too slow for any calculations. Look for an analog output.

Didn't see one in the manual. It's a pretty basic drive. We usually use ACS310 and ACS550 drives. I think we did put a ACS150 on a stand alone spool winder.

If the drive can't report it, you could install one (or 3) of these on the motor leads and connect them to an analog input on your PLC.
http://www.automationdirect.com/adc/Overview/Catalog/Sensors_-z-_Encoders/Current_-a-_Voltage_Sensors_%28AC_-a-_DC%29/Current_Transducers/AC_Current_Transducers_%28True_RMS%29

Thank you all of you for your quick response. According to your suggestion, I may need to add the current transducers to input signal to the PLC Analog card or replace with the suitable drive. The current transducers may be cheaper option to do so if there is no ACS310 and ACS550 drives in our stock. Could you please guide me how to implement if we have ACS310 and ACS550 drives and going to replace it.
Thanks


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A quick word of warning concerning CTs. Disconnecting them under load will result in extermely high voltage, and possibly an Arc Flash and/or fire.

How seriously should you take this? Well, a company that I used to work for (and long before I got there) burned down a four story apartment complex. Film at 11...

While I was there, our contractors clipped the leads on not one, but two CTs at the Meridian, MS site. Our customer was not amused...

So keep this in mind when (and where) you terminate the CT.

The one that mendonsy pointed you to is sweet, since the CT and the 4-20 converter is in the same unit. I would avoid the ones with the remote CTs since should someone clip the leads going into the converter it will definitely arc on you.

[FONT=&quot]Thank you rootboy. I will take your warning seriously and will update how it goes if I add the CT. It would also be great if someone post the implementation procedure and steps of working with Modbus RTU or TCP with either ACS310 or ACS550 and Modicon-Quantum or M340[/FONT]
[FONT=&quot]Thank you for your suggestion and time.[/FONT]

No problem.

As for setting it up for Modbus, as near as I can tell, you want to use the 485 option, make your Modicon the master and your drive(s) the slave(s), pick an address for each device, and set the communications up for whatever baud rate you like, 8E1 for the data format (8 bits, Even Parity, 1 Stop bit).

Then in your drives, load your drive current parameter (0104) into 5310 (just store 104 in 5310), this should now map the value that is in 104 (your current) into Modbus register 40005.

Back at the Modicon, have it read Modbus register 40005 in the drives.

Sounds simple anyway...

Thank-you rootboy! I will try with your procedure and will post it how it goes or require more information.
Appreciated your response.

Oh, and if you end up doing *any* Modbus work at all, get one of these:

http://www.usconverters.com/usb-rs485-converter-xs890

(which are currently back ordered, but should be in by the 6th)

And get the little nine pin connector to terminal strip adapter (or just sacrifice a serial cable). I do not recommend getting any adapter that has a terminal strip for your "knock around" converter. The little screws will gain their freedom from you and run off and hide in your laptop bag. It's the way to go for a permanent installation, but not for your personal unit.

I've had others such as the B&B unit, but this one is my favorite. It's been rock-solid, and has blinky lights. Never underestimate the value of blinky lights in serial communications.

The reason for this is that when (not if) you start having Modbus problems, it sure will be nice to plug in and see exactly what's going on on your network. Or more correctly, if anything at all is going on. It can save you a ton of frustration.

RealTerm is quite handy for seeing what malformed packets are on the network. And get one of the free Modbus scanner/Master/Slave programs for reading "good" packets.