3/19/2011 9:38 PM | |
Posts: 223 Rating:
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I also had to check the connection of panels to a plc. I concerns 4 mobile panels 177. Since there are no scripts available in this type of panel I used two tags in the panel connected each to a separate word in a datablok. The first word is continually increased in the plc. In the panel for that tag there is an event on change of value that writes the tags value to the second tag. The second tag is checked in the plc for continuous change. Both tags are updated cyclic continuous every 500ms. This works, but sometimes my panels freeze : no action is possible anymore on the panel, and also the tags are not updated anymore. Could this be because of the event on change of value every 500 ms? The four panels are connected to Profibus togegether with some 20 ET200S slaves. The profibus cycle time is about 15 ms. Because I thougt my communciation check was causing the freezing, I tried somthing else : I used the coordination area of the panel, in fact the startupbit that is set continuously. I check the startupbit continuously in the plc, and after the check I reset the bit every cycle. So, if the startup bit stays low for some time I know the panel isn't there anymore. This worked fine for one panel. Then I did the same for the other 3 panels. I supplied a separate datablok for the area pointers of each panel. When I connect more then one panel, I see a system message on the panel : interference on the bus', and the panels are not communicating with the plc. I don't understand why it works with one panel but not with more then one. Can someone help me on both 'solutions' I tried? Thanks Splitted from Connection check with panel. |
Last edited by: O_Moderator at: 3/21/2011 11:28 AMnew subject after splitting |
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3/22/2011 11:51 AM | |
Joined: 4/29/2010 Last visit: 1/20/2025 Posts: 1557 Rating:
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Hello, 1. Why do you reset the bit of the area pointer in the plc, this isn`t allowed. 2. It would be better to use the solution at this faq to show the cpu status: How can you visualize the current status of the CPU on a WinCC flexible operator panel? best regards |
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