10/23/2008 9:05 AM | |
Joined: 9/27/2006 Last visit: 9/1/2024 Posts: 12282 Rating:
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Hello simatic_user; Please provide a few more details on the situation you face: -Are you using PA-couplers or DP/PA links to connect your PA instruments? -Are your Motor starters DOL or VFDs? -Are only the PA instruments affected when starting the motors or are any readings on the DP side affected as well? If all your network is affected i would suspect harmonics (from a VFD) and/or ground loop issues. I can suggest the following small atttached manual, from PNO: Technical Installation guidelines for Profibus PA. Chapter 3.3.3 discusses shielding and grounding issues, it might help you. Can you check how the Couplers and the PLC chassis are connected to the plant clean ground? If you disconnect the ground connector between the PA-couplers and the plant ground, do you still have problems with the communications (this would indicate that signals are coming back through the grounding path)? Hope this helps, Daniel Chartier AttachmentInst_Guide_PA_2092_V22_Feb03.pdf (229 Downloads) |
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