Powerflex 70 upgrade Ethernet or RIO

We are preparing to replace an obsolete conveyor control scheme. The current system has a conveyor that accepts the part at high speed from the upstream conveyor then transfers it to the next conveyor at slow speed. This is acomplished with a motor tach, a Fenner closed loop speed controller, and a SECO DC drive. The 5/40E uses an ASCII module to set the high and low speeds on the Fenner.

The speed match does not need to be exact, 5% difference is fine. The part is very light, the difference in a loaded and unloaded conveyor will be almost nothing. With this in mind we think the closed loop speed control is overkill and are proposing a sensorless vector control with the powerflex 70. Since the timing of the ramp up and ramp down is pretty critical I was thinking of going with hardwired I/O to the drive, probably Flex I/O. (Please comment if you think this can easily be done over the network and therefore doesn't need to be hardwired)

Main PLC 5/40E Available communciation RIO, DH+, and Ethernet. The RIO is talking to 2 full racks and an AB IMC (I think this is also a full rack). The only thing on the ethernet is an Ultra5000. The DH+ is programming and 2 other 5/20s

So to my question, What is the best way to communicate with both the drives and the flex i/o? Would you put them all on RIO (I might need to add a scanner)? Should I communicate with the drive over ethernet and the flex I/O over RIO (The way I am leaning)? Am I going about this the wrong way?

Thanks for your thoughts.

If it were me, I'd go RIO directly to the drive. I think the PLC-5/40 supports 16 logical racks, so you've got plenty of I/O memory space and a low RIO node count.

Going to FLEX, then to hardwire substitutes the speed of the 1794-ASB and the Output module for the speed of the 20-COMM-R and the PowerFlex DPI converter. They're probably going to be comparable.

Ken - I must ask since you didn't elaborate, why RIO rather than some other communications solution? If the Op is going with the PowerFlex 70, my first thought is to do away with hardwired I/O.

IMHO, Ken, you are the man. That in mind, I really would like to hear your thoughts.

Steve

Since he has a PLC-5/40E, and the RIO channel is already there, it makes sense to install a 20-COMM-R module in the PowerFlex drive, set up for 1/2 Rack operation.

This covers speed control, discrete stop/start, and some feedback/parameter adjustment (via DataLinks), at a minimum hardware and footprint cost.

For this particular PLC-5/40E controller, the Channel 1B RIO scanner is the fastest method of communicating with a drive, except for discrete I/O in the local chassis.

With four adapters, you're looking at about 12 ms of RIO scantime, plus about 10 ms of RIO/DPI conversion inside the 20-COMM-R module.

I would use the PowerFlex 70EC for this application, if you're going with PowerFlex 70. The speed control is superior and the DPI processing is a bit faster.

Steve Etter said:

Ken - I must ask since you didn't elaborate, why RIO rather than some other communications solution? If the Op is going with the PowerFlex 70, my first thought is to do away with hardwired I/O.

IMHO, Ken, you are the man. That in mind, I really would like to hear your thoughts.

Steve

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The other networks the OP has are ethernet and DH+ and it is a best practice not to use these to control drives and IO.

Maybe to read non critical values out of the drive but it is not good practice to try to use the control word over ethernet on plc 5 or slc systems.

Just as a FYI also Ken rockwell is axing the 20-Comm-R at the end of this year.

Really ? That's a bizarre decision. I realize it wasn't as popular as the true CIP network interfaces, but it can't be that expensive to keep producing a tried-and-true accessory module.

Ah, well, not my problem anymore.

That was the news at the migration class at ROATM Atlanta two weeks back. I did not like to hear that because that is how I have been replacing 1336 force drives in our plc 5 systems when they die. I use the 20-COMM-R to put in PF 700 or 755 drives on plc 5 systems.

IIRC it was something to do with a chip that is the same as the 1336 drives and they can no loger get it made at a price that works for the low demand. I don't know how true that is but that was there story and they are sticking to it.

Thanks Ken, I now understand what you mean about the signal already coming through the RIO network, turning the Flex I/O into an unneeded middle man. I will probably go RIO directly to the drive.

I am having trouble finding anything about the powerflex 70EC, enhanced control, except in older documentation. It almost appears that this is a standard option now. Is this correct?

DAnderson said:

I am having trouble finding anything about the powerflex 70EC, enhanced control, except in older documentation. It almost appears that this is a standard option now. Is this correct?

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Yes, standard control has gone by the wayside, and was made more expensive than the EC version. I think it may still be possible to get the standard control for the PF700, but don't do it unless you have to keep spares for an existing system with the data already mapped out.

The size of the datalinks may be 32 bit words rather than 16 bit. We still have a boatload of PF700 standard control drives on devicenet, and switching to the EC can include a bunch of data shuffling depending on the controller and whether or not you're using data links.

Another thing to consider is if you were to go with Ethernet, you may have to upgrade your processor to handle the multihop necessary with a 20-comm-E. The manual says you must have series E, rev D.1 or higher for the plc-5 to access the drive. I set up a drive with a 20-comm-E and did not have a newer processor to install immediately, while it would connect eventually, it could take a long as 15 min to establish comms when powered up. I agree with Ken that RIO is the way to go if you have an older processor and don't want to spend the money on a newer version.