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  1. #1
    Join Date
    Sep 2010
    Location
    Peoria, IL
    Posts
    55
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    AB Powerflex VFD comm. to Siemens P1 FLN @ 9600 baud

    I have had hit and miss success hooking up trunks consisiting of one to six Allen-Bradley Powerflex 400 VFD's to FLN trunks in our Siemens control panels. Sometimes I hook them up and configure the drives and they just consistently talk perfectly without failure. Other times I can't get them to talk at all using all the same settings.

    What's really confusing me now, is that I can get the whole trunk to talk for maybe an hour or two and then lose communication to them all after that. They don't automatically re-connect and I have to go through and cycle power to the 5 that are currently on the trunk and then they will talk for a while again before losing communication.

    I am using application #2735 on a Siemens PXCM modular controller, wiring for the trunk is all daisy-chained 18ga. shielded. The drives are configured for 9600, P1 8-N-1, and I've checked for conflicting duplicate node addresses. What else can a check to ensure consistent communications?

  2. #2
    Join Date
    Apr 2003
    Location
    San Diego
    Posts
    19
    Post Likes
    I am facing the same situation at my site. Have you heard of fixes?

  3. #3
    Join Date
    Jun 2009
    Location
    Iowa
    Posts
    49
    Post Likes
    Quote Originally Posted by SMorrison78 View Post
    I have had hit and miss success hooking up trunks consisiting of one to six Allen-Bradley Powerflex 400 VFD's to FLN trunks in our Siemens control panels. Sometimes I hook them up and configure the drives and they just consistently talk perfectly without failure. Other times I can't get them to talk at all using all the same settings.

    What's really confusing me now, is that I can get the whole trunk to talk for maybe an hour or two and then lose communication to them all after that. They don't automatically re-connect and I have to go through and cycle power to the 5 that are currently on the trunk and then they will talk for a while again before losing communication.

    I am using application #2735 on a Siemens PXCM modular controller, wiring for the trunk is all daisy-chained 18ga. shielded. The drives are configured for 9600, P1 8-N-1, and I've checked for conflicting duplicate node addresses. What else can a check to ensure consistent communications?
    The first thing I would try is to drop the baud rate to 4800. Any P1 device that was certified by Siemens is only tested and certified at 4800, as that is the only baud rate most of the P1 devices run. A standard P1 TEC only runs at 4800, and is not adjustable. The higher baud rate is not needed at the p1 protocal is a COV based one, so the devices send the main panel changes, the panel does not have to poll for it.

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