6/23/2016 4:14 PM | |
Joined: 9/27/2006 Last visit: 9/9/2024 Posts: 12282 Rating: (2682) |
Hello joojooe; In our projects, we tend to plan our design in the opposite way. We start by determining the number of nodes we will be using in our Profibus network: masters, slaves, HMI, drives... This helps us calculate the number of segments required: 32 nodes per segment maximum, so 31 nodes + 1 repeater/segment. Next we try to evaluate the distance that the copper wire will travel to connect all the nodes, using the mechanical layout of the plant. Often it is not possible to do this at design time with any degree of accuracy, try to estimate it as best you can; adjust when the final plans have been produced. Now you know the number of segments and approximately the distance to cover. See the attachment for a graph of distance vs bus speed for a single segment; this is from a PPT presentation from Profibus International on Best Practices for Profibus networks, a good quick reminder for our projects: http://www.profibus.com/uploads/media/03_PROFIBUS_Design_good_practices.pdf With this information we select the bus speed we will be operating at. If we can operate each single segment at 500 kB and higher we are generally satisfied, and do not add any repeaters. Of course higher speeds might be preferable for certain applications (pick and place or packaging for example); in case you decide your project needs a higher speed than is available with the original parameters of the network, the calculate how many extra repeaters you would need. Remember to adjust the bus parameters for Profibus (double-click the Profibus line in the configurator to open that menu) and add the correct number of repeaters in the network. This allows the Profibus configurator to calculate the correct settings for Profibus data exchanges. Hope this helps, Daniel Chartier |
Last edited by: dchartier at: 6/23/2016 9:17:56 PM |
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This contribution was helpful to1 thankful Users |
6/24/2016 9:11 AM | |
Joined: 6/23/2016 Last visit: 11/2/2023 Posts: 2 Rating: (0) |
How could I know that current project runs smoothly at 187.5 kHz not 500Khz or any other rate? |
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