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| 10/20/2008 9:48 PM | |
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I have one SIMATIC 555 CPU and there are near about 60 profibus slave connected on the it through couples of Profibus router. I am unsure what you are referring to as a Profibus Router? Are you talking about a repeater? You should have at least 2 repeaters since there is a limit of 32 nodes on a segment. At 1.5 MBaud the maximum segment length is 200 meters. I have seen problems when the segment length exceeds 200 meters without a repeater. Also if you go to higher baud rates the segment length is reduced to 100 meters. A BT200 is a great tool for troubleshooting the Profibus network. Your Local Siemens representative may have one you can use to check your network. Last week we saw that some slave lost communication for some time and regained it after some time. This happened three to fout times. what could be the cause of that? The most likely cause is a loose connection or noise. Are these nodes on the same segment or on different sefgments. Is it always the same nodes or is it random? what changed before you started having problems. Did you install new equipment in the vicinity. Did you move a node, add a node, delete a node? Here are my doubts: 1) Is it advisable to put all these 60 slaves with one profibus master and also with 1.5 Mbps? There is nothing wrong with having 60 slaves on a single profibus network running at 1.5 MB. The 555 can support up to 112 master and slave addresses. Are the slaves 505 RBCs, ET200, Drives or 3rd party devices? 2) Is there any possibility with Shielding of the cables? Do I need to use shield everwhere? All cables should be shielded and the shield should be in contact with the metal Profibus connector. I have attached a few pages from the system manual on Profibus installation. 3) Can I capture the first slave or node where this problem occurs for the first time? if yes then how. Status words 03 thru 09 contain the status of the DP slaves. The value 1 signifies the slave is not present or failed. You could monitor the bits for the 60 slaves you have and capture when the slave fails. You could narrow down the monitoring to the specific slaves that failed in the past. You can store it in a shift register, use it to initiate an alarm on you HMI, ....... Dutta Bill Attachmentprofibus Pages from 5x5sm.pdf (707 Downloads) |
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