SLC 505 controlling PF753 over ethernet

[Sun TC]

My counterpart and I spent the whole day today trying to setup a SLC500 to send a start command and speed reference to 20 HP powerflex 753 today. We downloaded Rockwell's manuals on the controlling the drive via Ethernet and went through the example using msg functions to send info to the drive. We tried to Betty Crocker the code as best we could but could never get it to work. We were able to set up a working EEM message to write the desired speed to parameter 546, but never got the drive to start and run. We should have most of the morning to get it working, but after lunch we will have drop back and punt and go old school terminal control to get it going if we haven't figured it out. Any insight into making this work would be appreciated. I hate to concede defeat.

 

[Ken Roach]

Welcome to the PLCTalk Forum !

I've been emphatically arguing against this sort of AC drive control with SLC-5/05 and MicroLogix 1100/1400 controllers for many years, to the point where folks get out the popcorn when the topic comes up on PLCTalk.

Can I ask why you decided to try this control architecture ? I'm genuinely curious about what kind of sales effort or technical documentation is making folks try to run modern PowerFlex drives with the archaic SLC controllers.

I very strongly prefer "old school terminal control" for start/stop of the drive, if an SLC-5/05 is the controller. You can use MSG or EEM instructions to update the speed reference or other runtime parameters, but using messaging for start/stop just isn't meant to be done with SLC-500 controllers, despite the technical features that make it possible.

 

[AutoMax]

+1 to Ken. It can be done, but it's unreliable. Some 500 series controllers support Ethernet, but not implicit Ethernet/IP connections as we have come to take for granted. If you want to network control a drive with a SLC 5/05 use Profibus. (I suppose DeviceNet fans would take exception to that, if there were any DeviceNet fans...)

 

[rupej]

I've done it with a ML1400 to a PF525, should be fairly similar to your situation. I've had no issues running it for about 2 years now, but I was careful to include error checks and safeguards.

As I recall, the tricky parts were knowing what integers in the drive to write to, and also having to write a "timeout" value when the drive first starts (I just wrote it continually every few seconds to make it more robust).

That said, it didn't gain much over the old school terminal block method.

Any specific questions on your issue?

 

[Helliana]

I've done it with a ML1400 to a PF525, should be fairly similar to your situation. I've had no issues running it for about 2 years now, but I was careful to include error checks and safeguards.

As I recall, the tricky parts were knowing what integers in the drive to write to, and also having to write a "timeout" value when the drive first starts (I just wrote it continually every few seconds to make it more robust).

That said, it didn't gain much over the old school terminal block method.

Any specific questions on your issue?

Using a Micrologix1400 would also be the best case scenerio for using a Logix500 based controller to control a modern drive via explicit messages. Its surprising to many people that the $800 micrologix 1100/1400 family has a significantly more powerful network hardware than a $6000+ SLC 5/05. A 5/05 network card can easily be overloaded with a few messages and an HMI, causing interment issues with the start and stop singles being messaged. Your best bet is just to pull two extra wires with the network cable and start the drive via a relay contact.

 

[Sun TC]

We got everything working this morning and seems to be doing OK. The big reason we decided to go this way is because we added this drive to replace what was previously a diaphragm pump with a Lobe type PD pump and the old SLC didn't have enough IO left to do everthing we wanted to do. There was no empty slots and no available analog outputs, so we weren't going to have a good way for the operators to control pump speed from the panelview 550. I would not do things this way again in the future if I could help it.

 

[Sun TC]

Most of our guidance came from the 20-Comm-E manual and this publication from Rockwell "Controller Examples for EtherNet/IP Network Communication
with PowerFlex 750-Series Drives". We are sending the drive the speed command, accel and decel times, and starting and stopping the drive. The only things on the network are the Panelview 550, the SLC, and this drive, and the programming grace port. I will take you guys advice to heart and keep a close eye on the performance of this setup. This project sure made me appreciate Logix 5000 controllers even more.

 

[WillPollock]

Sun TC,

Curious how reliable this turned out to be for you? Do you have any example code you are able to share, or just the class/instance/attributes for the start command, and feedback from the drive?

Thanks!