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Bob A.

Control Of PF40 via 22 Comm E via EtherNet/IP

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Hi Guys, Had a troublesome problem recently with control of a drive over EtherNet/IP. There is a drive that runs twice a minute that sometimes would not start even though the command was sent. After a lot of troubleshooting effort, and three Tech Connect sessions, it was determined that the Stop Command was not gone when the Start Command arrived and so it was ignored. The problem was based on the fact that I was using a "NOT Run" condition in the logic to send the Stop and when "Run" was sent, it would get there before Stop was Off about 5% of the time. I'm now using a timer to release the Stop shortly before the Start is sent and the problem has been solved. Best Regards, Bob A.

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We always hard wire the start/stop function. Everything else is by communication (whether Ethernet or RS485) And I don't trust 'buffers'. Each message is sent only after the completion of the previous one. Edited by b_carlton

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Another method you can use is to MOV the whole command word. This should ensure no overlap of command bits, and also guarantees that the auto/local mode and all other bits are what you want for a given mode. it ends up being pretty clean compared to having to account for potential asynchronous updates. We do this on Devicenet drives. There's a rung for each mode, and a branch for the speed command, and a branch to copy the whole command word. Matter of fact, in a Logix5000 controller, the CPS instruction might be the ticket. And if you are trying to control them with Ethernet Messages from a SLC or Micrologix, then re-read your sub-title.(What not to do...) Edited by OkiePC

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This is what I do (if I am reading the original post correctly) Start Command and not Drivename:I.Active then turn on Drivename:O.Start that way the Drivename:O.Start output to the drive drops out as soon as the active feedback is received from the drive then for stopping: not Start Command and Drivename:I.Active then turn on Drivename:O.Stop Same as before, Drivename:O.Stop output to the drive drops out as soon as the active feedback from the drive goes low.
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That's nice. I use the active bit for stopping just like you have it if I need many of the functions, and go ahead and code them all, OTU-ing those I want disabled. I hadn't thought about the momentary start being done that simple. I do believe my start bit stays high until a stop is issued... Thanks, Paul

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Hi Guys, It has been interesting to see how you all have addressed this requirement. I've been tied up for a few weeks and while my last patch has worked perfectly, it is not really a sexy as it should be. I have spent some time watching the Active bit and others, but don't have an exact definition of what it represents. from Bill Fletchers post, it appears that it is more useful than I initially thought. This will definitely get some more attention. Bernie C...Like you, I approach this from a conservative point of view and I fully expected to need the hard wired method to have positive control. When I did the initial testing of the Start Stop functions (using PF40 over EIP) back in 2005, it worked fine and so I deligated the hardwired control as a backup. I see that now, there is a secondary safety circuit in some drives for assuring that the drive cannot motor (see PF 755) . I would have bought that, if it had been available in a timely fashion. Thanks for all the great feedback. You guys are great! Best Regards, Bob A.

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