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Communication is interrupting in low baud rate

Created by: epro at: 4/19/2011 6:15 PM (12 Replies)

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4/19/2011 6:15 PM	Rate (0)
epro Posts: 62 Rating: (0)	Dear all, Our CPU is S7 414-2DP. 1^st DP slave ET 200S (5 mt distance) 2^nd DP slave ET 200M (300 mt via FO and OLM) 3^rd DP slave ET 200M (300 mt via FO and OLM) 4^th DP slave CP 342-5 connected with another 300CPU (50 mt via profibus cable) The 300 CPU has a demand of 19.2 kbps speed. With this speed we have a periodical bus fault to communicate with CP342-5 (1 or 2 in every 5 min). But when we increase the speed 1.5 mbps there is no bus fault. We increase the retry limit, put communication blocks in interrupt OBs for time synchronization but still we have bus fault. Our peripheral I/Os size in this bus is 24 bytes (for slave 1^st , 2^nd and 3^rd ) and communication data for CP is 80bytes called by SFC14 and 15 (DP send and DP receive). In OLM we don’t have any ring connection.
epro Posts: 62 Rating: (0)	Last edited by: epro at: 4/19/2011 7:06 PM
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4/21/2011 10:53 AM	Rate (0)
epro Posts: 62 Rating: (0)	Is there no body to help?
epro Posts: 62 Rating: (0)
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5/27/2011 3:38 PM	Rate (0)
epro Posts: 62 Rating: (0)	Nobody to help me????
epro Posts: 62 Rating: (0)
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5/27/2011 3:55 PM	Rate (0)
IBN-Service Posts: 8946 Rating: (999)	OK, lets try. Why, in hell, you do not use 1.5 mbps if it is running without problems?
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This contribution was helpful to 1 thankful Users epro

5/27/2011 8:14 PM	Rate (0)
epro Posts: 62 Rating: (0)	Thanks. At last some one come. The reason behind it, that we have to communicate with a furnace PLC and their requirement is 19.2 kbps.(viaCP 342-5)
epro Posts: 62 Rating: (0)
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5/27/2011 8:34 PM	Rate (0)
IBN-Service Posts: 8946 Rating: (999)	epro Thanks. At last some one come. The reason behind it, that we have to communicate with a furnace PLC and their requirement is 19.2 kbps.(viaCP 342-5) You are welcome. My opinion: If the bus run well with 1.5 mbps, it will be also OK with 19k! Perhaps the bus is not the problem but the furnace PLC? It need 19k, so it will only working if the speed is 19k. If you run with 1.5M, there is no problem because furnace PLC is not active... May be, that is the reason?
IBN-Service Posts: 8946 Rating: (999)
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5/27/2011 9:05 PM	Rate (0)
epro Posts: 62 Rating: (0)	Thx, But we checked by removing the furnace PLC then also we have bus fault in 19.2 kbps. With Fur PLC the count increases. Is it an issue for OLM or what else? the total I/O load also seems to be ok.
epro Posts: 62 Rating: (0)
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5/27/2011 9:19 PM	Rate (0)
IBN-Service Posts: 8946 Rating: (999)	Check diagnostic buffer to see, what station caused the error. Very helpfull is also a diagnostic repeater, but it is a little bit expensive.
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5/27/2011 9:25 PM	Rate (0)
epro Posts: 62 Rating: (0)	Tomorrow I will be able to tell you the diagnostic buffer Sorry we don't have any diagnostic repeater. Thx again for trying to help me.
epro Posts: 62 Rating: (0)
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5/27/2011 9:27 PM	Rate (0)
IBN-Service Posts: 8946 Rating: (999)	Please check also: Is the OLM included in Profibus configuration? (settings for bus in HW-config)
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