Navigation
Recommendation for Master/Slave simultaneously - Profibus DP
Created by: Pedro Ascencio at: 7/9/2012 5:54 PM (7 Replies)
Rating 
Thanks 0
8 Entries
| 7/9/2012 5:54 PM | |
|
Posts: 56 Rating:
|
Dear Experts At this moment at time, in our control systems, we need to communicate a PLC S7-400 with the DCS, using profibus DP. Currently, the PLC isthe "master" of several remote racks (ET200M) slaves. On the other hand,for the DCS-PLC link, the DCS needs to be the "master" and PLC its only one "slave". My question is: Could be the PLC a Master and Slave in the same Profibus network simultaneously ?. I attach an squeme for your reference. Maybe would be better to split in two networks, with a dedicated link for DCS-PLC link, usign for instance: a CP 443-5 or IF964-DP interface. Please, could you recommned us any soluction? Many thanks in advance AttachmentTopology_proposal.pdf (184 Downloads) |
Last edited by: Pedro Ascencio at: 7/9/2012 6:01 PM |
|
| 7/10/2012 12:19 AM | |
Joined: 9/27/2006 Last visit: 3/21/2025 Posts: 12344 Rating:
|
Hello Pedro; Alternatly To VishP's suggestion, you could more simply use a DP/DP coupler to exchage data between the 2 DP masters on the same network. The DP/DP coupler has 2 seperate Profibus connectors, and acts as2 seperate DP slaves, one connected and configured to each DP master on the bus.. Whatever master 1 writes to its "side" of the DP/DP coupler can be read by master 2, and vice-versa. You can echange up to 244 bytes of data (both read and write) between the 2 masters with the DP/DP coupler. You can read more on this module in the following document: DP/DP coupler Hope this helps, Daniel Chartier |
| 7/10/2012 2:14 PM | |
|
Posts: 56 Rating:
|
Many thanks for your advices. Reganding VishP recommendation, I prefer to leave the second MPI/DP port free for connecting directly a PG, specially when it is necessary maintenance or overcome recover problems. With respect to dchartier advice, I do notknow ifDP/DP works well because DCS is master of one profibus segment andits slave belong to the other profibus segment (PLC). As you can see, PLC is masterof ET200M in theother segment. I attach thesqueme. I think that to add a new profibus module is more clear, dispite it is more expensive. Many thanks for your help. AttachmentTopology_proposal.pdf (164 Downloads) |
| 7/11/2012 2:54 AM | |
Joined: 10/7/2005 Last visit: 3/20/2025 Posts: 3042 Rating:
|
Hello Pedro Ascencio I'd go for Daniels suggested DP/DP coupler solution too, also in lightof the followingadvantage: 244 Bytes of Inputs and Outputs is the limit of a DP Slave. If you go for a CP443-5 solution and 244 Bytes turns out to be not enough, you'd need to add another rather expensive CP443-5 to your S7-400 (providing you have rack space left). With the DP/DP Coupler solution, you'd simply put a second(or third or fourth) DP/DP coupler "in parallel" with the first one (each will give you 244 Bytes of I/O to exchange). To be fair, the advantage of the CP443-5 solutionis that it has (or can have) its own Profibus network, so it won't add to the Profibus scan time of your ET200M based Network (using the full 244 Bytes of inputs and outputs will "cost" you an additional3.8 ms at a Profibus DP baudrate of 1.5 Mbps). I hope this helps |
|
Cheers |
|
Follow us on