Remote I/O or Distributed I/O?...
Tharon said:
Is it possible to use a Powerflex 525 as a Remote IO?...I have a CompactLogix PLC controlling a PowerFlex 525 via Ethernet/IP
I could be really smart and say "No. It is not." But, I'm not trying to be smart, just particular, if you'll forgive me.
Remote I/O is Distributed I/O, but, Distributed I/O is not Remote I/O, even though the I/O happens to be remote from the controller. It's just Rockwell/AB terminology but I always feel it can lead to confusion when these two terms are mixed up.
The above is just a distinction I like to make as the long standing "Remote I/O" or "RIO" option is quite specific in the Rockwell world as a particular means of Distributing I/O and does not refer to all or any means of Distributing I/O. For I/O that is remote to the controller's backplane, but not specifically "Remote I/O" as in "RIO", I would use the term "Distributed I/O". RIO is Distributed I/O, as is EtherNet/IP, DeviceNet, ControlNet, etc. I would not, as best practice, call EtherNet/IP "Remote I/O", even though I'm sure most will understand what you mean.
This is just some passing advice on the topic at hand for all and not in particular to this case...
Tharon said:
...I'd like to get an 0-10V analog signal back to my PLC from that remote location. Is it possible to wire it to the 525's Analog input and then read that value via Ethernet/IP?...
While we can say it is possible, I am considering here more the question of should we?...
I would say, if needs must then needs must, but, if a device signal is required back to the controller, and it is not directly related to the drive or its application, then I would advise not adding it in through a drive's Datalinks or explicit messaging. This can save you a lot of work up front but possibly add a level of complexity that someone else may not appreciate down the line. If the signal is not related to the drive, in any way, then I would, at a minimum, attempt to add the signal device to the network as a node, and communicate the data more transparently. That is, of course, if the end device supports such a network, or can be converted to as such. It may be possible to provision the device onto the network close to the drive location, which is already on the same network i.e. add it to the network where the drive is already connected. A local switch, for instance. If the network topology somehow dicates a "home run" cabling, then again, it's back to the "needs must" scenario. If you must get it directly back, but it is not related to the existing application, then I would advise attempting to do so. Else, you add it in through the drive in a less transparent manner.
If the signal device is directly related to the drive and its application then I would wholeheartedly support the use of Datalinks to communicate such signals.
But explicit messaging?...
Tharon said:
...Is there an Explicit Message type I could use or something like a GSV?...
Another point to be careful with when choosing to use Datalinks to and from a drive as opposed to explicit messaging is the drive's Non-Volatile Storage (NVS). When you use explicit messaging write to the DSI Parameter Object you are also writing to NVS. If you write quite often in a cyclical manner then you may prematurely exhaust the life of the NVS. This will render the drive faulty and it will need replacing.
If you use Datalinks then the written data to the DSI Parameter Object is not saved to NVS, but is lost on power cycle. This will save the life of the NVS. This is why you are advised to use Datalinks for frequent parameter changes in these drives.
There is also the option to disable NVS writes entirely (C121 [Comm Write Mode] = 1 “RAM only”), but do note that any current parameter settings will be lost on power cycle and will require reinitialization.
And to finish off, here is some info on how you would do the opposite to the above request i.e. configure Datalinks to allow a controller write to an analog output connected to a PowerFlex 525 drive...
531277 - PowerFlex 525 drive: Analog Inputs and Outputs / Use of PLC and Datalinks to analog output
Access Level: Everyone
Just to be clear - I am not saying that the signal in your case, Tharon, is not related to the drive or its application. But more that the above should possibly be considered where it isn't related. The above is intended more as "best practice" advice, than anything else.
Regards,
George