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why is that there is a limitation on the number of bytes that can be communicated!!!!

Created by: SPV at: 6/5/2009 3:48 AM (7 Replies)

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6/5/2009 3:48 AM	Rate (0)
SPV Experienced Member Joined: 6/28/2007 Last visit: 12/13/2023 Posts: 61 Rating: (4)	Hey Friends Can any one let me know why is that there is a limitation on the number of bytes that can be communicated!!!! Is it that A Y link is always a slave network or can it also be used as a master??
	Best Regards & Thanks in Advance SPV
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6/5/2009 12:13 PM	Rate (0)
Darius Platinum Member Joined: 9/28/2005 Last visit: 8/27/2024 Posts: 2957 Rating: (242)	Hi, This question must go to Y link developers. It consists of DP couplers and I thinkbyte limitation isprotocol dependant.
	Best regards, Darius
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6/5/2009 9:33 PM	Rate (0)
jklm Platinum Member Joined: 12/22/2006 Last visit: 1/25/2022 Posts: 1742 Rating: (308)	Hello, The Y link creates a network transition from the redundant DP master system of an S7-400H to a non-redundant DP master system. This means that devices with only one PROFIBUS DP interface can be connected to a S7-400H as switched peripherals. For the S7-400H, the Y link is a DP slave. Ans a DP slave may only have 244 bytes of netto data (a Profibus frame cannot be longer than 256 bytes by definition).
	Best regards jklm Suggestion was helpful? Feel free to rate it.
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6/5/2009 9:41 PM	Rate (0)
SPV Experienced Member Joined: 6/28/2007 Last visit: 12/13/2023 Posts: 61 Rating: (4)	Hey EDR If that would be the case the even DP/PA Coupler is a creating a new network whcih is a transitions between the Redundent Network and the PA network....... the point i see which is open here is that is the limitation of the bytes is due to the redundent network or due to the electornics design of the Y Link.... Due to this Limitations non of the HMi's Cannot be added and henforth call for 2 repeater whcih doesent look as a well structured system
	Best Regards & Thanks in Advance SPV
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6/5/2009 11:28 PM	Rate (1)
daga Gold Member Joined: 3/18/2009 Last visit: 5/6/2024 Posts: 306 Rating: (94)	Hi SPV, SPV the point i see which is open here is that is the limitation of the bytes is due to the redundent network or due to the electornics design of the Y Link.... I do not agree. I beleive that edr and Darius are correct. It is a protocol limitation. SPV If that would be the case the even DP/PA Coupler is a creating a new network whcih is a transitions between the Redundent Network and the PA network....... Even in DP\PA type network transition you cannot exceed 244 bytes i.e you cannot have PA devices on a single link with total cyclic input or output data exceding 244 bytes. However for PA, we rarely encounter this limitation as in most cases the current limit of the coupler is the bottleneck and not number of bytes. regards.

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6/6/2009 8:40 AM	Rate (0)
Darius Platinum Member Joined: 9/28/2005 Last visit: 8/27/2024 Posts: 2957 Rating: (242)	Hi, SPV Due to this Limitations non of the HMi's Cannot be added and henforth call for 2 repeater whcih doesent look as a well structured system HMI system CAN be added to Y link as well. See this thread /tf/WW/en/Posts/30726#top
	Best regards, Darius
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6/8/2009 12:05 AM	Rate (0)
H-H Platinum Member Joined: 7/2/2008 Last visit: 8/26/2024 Posts: 928 Rating: (308)	Hello Darius, Darius HMI system CAN be added to Y link as well. I think your words are much generic. The only HMI component (If we agree that it's an HMI) that can be connected through Y-Link is the Push Button Panel because it's the only DP-Slave in HMI family. Any other HMI panel can never be connected through Y-Link because they are all DP masters while the main function of Y-Link is to connect one sided DP slaves to the S7-400 H master. Best regards. H-H

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6/8/2009 7:13 AM	Rate (0)
Darius Platinum Member Joined: 9/28/2005 Last visit: 8/27/2024 Posts: 2957 Rating: (242)	Hello, H-H The only HMI component (If we agree that it's an HMI) that can be connected through Y-Link is the Push Button Panel because it's the only DP-Slave in HMI family. Yes, you're right .
	Best regards, Darius
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