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S7 313-2dp DP Slave, DCS Master, Best solution

Created by: Info1 at: 1/25/2011 3:46 PM (4 Replies)

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1/25/2011 3:46 PM	Rate (0)
Info1 Posts: 23 Rating: (0)	Hi, I have almost 20 313-2dp PLCs. I want to transfer data from them to a DCS (DELTAV). I am planning to use the DP port on each PLC and set each up as an intelligent slave. The DCS acts as master for the network.A good solution? The DCS will only be monitoring the data sent and we shouldnt need to send data from the DCS back to the PLC. I presume I then need to to use SFC 14,15 rather than DP_SEND,DP_RECV, for comms to the DCS. The other option is to use a DP DP Coupler on each PLC but does this option only allow transfer of I/O whereas the slave option will allow me to transfer data blocks made up of bits/words. Thanks, TS
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1/25/2011 4:21 PM	Rate (0)
dchartier Grandmaster-Expert Joined: 9/27/2006 Last visit: 9/16/2024 Posts: 12282 Rating: (2684)	Info1 Hi, I have almost 20 313-2dp PLCs. I want to transfer data from them to a DCS (DELTAV). I am planning to use the DP port on each PLC and set each up as an intelligent slave. The DCS acts as master for the network.A good solution? The DCS will only be monitoring the data sent and we shouldnt need to send data from the DCS back to the PLC. I presume I then need to to use SFC 14,15 rather than DP_SEND,DP_RECV, for comms to the DCS. The other option is to use a DP DP Coupler on each PLC but does this option only allow transfer of I/O whereas the slave option will allow me to transfer data blocks made up of bits/words. Thanks, TS Hello TS; If you plan on using the integrated DP interface of the S7-313Cs as Profibus-DP slaves, you will not useDP_Send/DP_Rcv (these functions are used when you have a CP 342-5 processor as DP imnterface).You will have to use I/O address areas in the S7 slavesfor data exchange with your DCS. Look at the following sample configurations of S7-300 slaves; I think you should concentrate on the second case, where the S7 slave and the S7 master belong to seperate projects, it will be closer to what you want to do with your DeltaV master. http://support.automation.siemens.com/WW/view/en/19449428 Orcompare withthis sample configuration where a S7-300 is set as a slave to a S5 PLC, this should be again close to a communication toa 3rd-party DP-master setup . http://support.automation.siemens.com/WW/view/en/6709721 In both case note that you will need to select IO addresses for the Profibus data exchanges. As slaves, you will not need SFC14/15 in the S7-313Cs,.These functions are programmed only in a S7 DP-master. You will have to use whatever functions are available in your DeltaV system to program consistency of data exchanges with its slaves. Hope this helps, Daniel Chartier

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1/26/2011 10:27 AM	Rate (0)
Info1 Posts: 23 Rating: (0)	Thanks for that, I was working from memory where I used to use SFCs for comms. I see now I can simply map to the Process Image. The DCS side is also straightforward to set up. To use a DP DP Coupler-is that a more restrictive option. Can I only forward on Inputs/Outputs rather than Data Blocks as per the DP Port.
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1/26/2011 3:37 PM	Rate (0)
dchartier Grandmaster-Expert Joined: 9/27/2006 Last visit: 9/16/2024 Posts: 12282 Rating: (2684)	Hello TS; Using a DP/DP coupler allows 2 masters to exchange data over Profibus-DP, each sending data to one of the 2 slave interfaces of the DP/DP coupler. It is a practical and low-cost option when PLCs cannot have a slave interface configured, for any reason, and Profibus-DP is the medium of data exchange. But in your case I do not believe it would be an advantage, as the S7-313C can easily be configured as a slave (no extra hardware to purchase) and the amount of data exchanged would have the same limits in both cases: 244 Bytes each way. For more details, have a look at the DP/DP coupler manual: http://support.automation.siemens.com/WW/view/en/1179382 Hope this helps, Daniel Chartier

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1/26/2011 10:17 PM	Rate (0)
fritz Diamond Expert Joined: 10/7/2005 Last visit: 9/17/2024 Posts: 3020 Rating: (1054)	Info1 I was working from memory where I used to use SFCs for comms. To use a DP DP Coupler-is that a more restrictive option. Can I only forward on Inputs/Outputs rather than Data Blocks as per the DP Port. Hello Info1 I agree with everything that Daniel stated, but would like to add that you will work with I/O's in both cases (DP/DP coupler or CPU as DP Slave), so the DP/DP coupler is NOT a more "restrictive" option (you can also use SFC14/15 in both cases which will take care of the DB to I/O interface as well as the data consistency). As a matter of fact, the DP/DP coupler is a somewhat less restrictive option as you could have more than one DP/DP coupler as the link betweentwo DP Masters and each will allow you to exchange up to 244 Bytes of I/O's(whereas if you make your CPU a DP Slave you will be "limited" toa max of 244 Bytes of I/O's which may be plenty for what you need to do though). I hope this helps
	Cheers fritz The advice and opinion given in this thread is that of the author and does not necessarily reflect the views of I S Systems Pty Limited. To find out how I S Systems can help you with your automation needs please visit www.issystems.com.au.
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