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Connect 2 315DP on Profibus

Created by: GIH at: 6/18/2007 10:44 AM (9 Replies)

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6/18/2007 10:44 AM	Rate (0)
GIH Posts: 11 Rating: (0)	Hello I need to connect two 315 2dp systems together and have loads of questions. I want to use Profibus. The first 315 is a control system for a machine and is working. It has lots of Profibus bits and pieces spread all over it. I need to send information to this system and also take some from it. When to start my system and some other parameters. I have setup a data block that I want to send and receive in my PLC. I don’t have access to this PLC as such to play with it. So does the new PLC I am working with. (MINE) have to appear in the existing machine PLC connections setup? I would prefer it does not have to but if this makes life difficult it is not a big problem. The existing PLC is a master. Do I have to be a slave? What functions do I use to send data about? And how do they work? I do have two 315 2DP two play with. (lucky me eh). I have connected these with a Profibus cable but that’s about it apart from wading through loads of help files and things, that just made more questions for me! I am very much a Profibus & Siemens novice so as much help as possible please. Thanks
GIH Posts: 11 Rating: (0)
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6/18/2007 12:03 PM	Rate (0)
J_Bell Posts: 5822 Rating: (412)	Dear GIH, sadly you have only a CPU 315-2 DP. In this case you can not use a S7-Connection to access the Data on the DP Master CPU. The only way, besides the us of additional CPs to transfer the Data, is to use DP. There you have two ways, you either configure the second PLC as DP Slave and you get or store the Data this way, or you use a DP/DP Gateway which is DP Slave on both sides. Depending on this you will always have to change the Configuration of the DP Master. This is due to the fact that you change the PROFIBUS and this requires changes in the Bus settings for the PROFIBUS Network. Needless to talk about the Configuration and setting of the amount of Information you want to transfer in between the two PLCs. I hope I could help a bit. Best regards J_Bell
J_Bell Posts: 5822 Rating: (412)
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6/19/2007 9:46 AM	Rate (0)
GIH Posts: 11 Rating: (0)	I thinks it's best then if I set the first PLC as master and mine as slave. Can't find how to set the PLC to a slave.....? What is meant by "CP"? In the software do I use function DP_SEND and DP_RECV? How do these functions work? The block shows CPLADDR is this the DP address I have 2 on the master and 102 on my slave when I set it slave or find out how to!!. The data to sendusing thisfunction block is that the SEND? How is the data set up. Can it be a common data block? How will the data appear on the other end. Do I just use a setup of the same data block on both PLC,s Heres what I need to do. data block { parm int parm int parm int machine start BOOL ok to start BOOL dont start BOOL } Master sends the data block.... Slavechecks the data block machine start parm and changes the ok to start or dont start then updates the parmspasses the data block back to the master to run the machine and put the params on the HMI for the operator to look at. The data block is bigger than this about 50 bytes. Where do I keep my comms blocks? What OB's are best? Will this use interrupts. Can thecomms start interrupts? Sorry if I appear a bit dim. This is notexactly my field of work normally.
GIH Posts: 11 Rating: (0)
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6/19/2007 10:44 AM	Rate (1)
Hulzhex Gold Member Joined: 8/25/2005 Last visit: 1/29/2025 Posts: 1162 Rating: (111)	Hello GIH, CP means Communication Precessor. This is a special interface for connecting for example to PROFIBUS. Only if you are using the CP 342-5 you have to program DP-SEND and DP-RECV. Think this page could be helpfull: Training material downloads Best regards Sabine

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6/19/2007 12:09 PM	Rate (0)
GIH Posts: 11 Rating: (0)	WOW. All the training notes are here for what I need to do. Can't thank enough. Just quickly. Cana DB block be assigned as the address range. Or just absolute memory in the symbol table. https://www.automation.siemens.com/download/internet/cache/3/1370368/pub/de/d06_cpu315_cpu315.pdf Page 34
GIH Posts: 11 Rating: (0)
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6/19/2007 12:12 PM	Rate (0)
GIH Posts: 11 Rating: (0)	Page 17 sorry. Getting excited....
GIH Posts: 11 Rating: (0)
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6/19/2007 12:18 PM	Rate (0)
Hulzhex Gold Member Joined: 8/25/2005 Last visit: 1/29/2025 Posts: 1162 Rating: (111)	Hello GIH, you have to copy your data to I/O-Area. Sabine

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6/19/2007 12:43 PM	Rate (0)
GIH Posts: 11 Rating: (0)	I thought i/o area is just the physical hardware attached to the cpu? My digital input, output and analog inputs and outputs? I would like to send some calculation data thats in my data block?
GIH Posts: 11 Rating: (0)
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6/19/2007 12:49 PM	Rate (0)
J_Bell Posts: 5822 Rating: (412)	Dear GIH, as Hulzhex mentionedand the Material shows, if you use DP Master / Slave with the CPU you can only access the IO Area of the CPU, no Memory and no DBs. So if you plan on transfering Data you will have to transfer it over the In- and Outputs of the CPU mapped to DP. Please remember you can not write to Inputs... only to Outputs. Best regards J_Bell
J_Bell Posts: 5822 Rating: (412)
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6/19/2007 11:38 PM	Rate (0)
Jesper Pedersen Posts: 279 Rating: (30)	Ama little bit confused about the task given. It sounds like GIH has to exchange data with an existing 315-2DP plc, but he cannot alter anything on it. Surely, to implement the desired data exchange at least some software has to be added or modified on the existing plc. So it should also be possible to say add the new 315-2DP as a slave on the existing 315-2DP. Here are GIH's options as I see it: 1. Let the new 315-2DP be a slave on the existing 315-2DP that is then master. Data exchange via i/o areas. Advantage:Least expensive because no other hardware has to be purchased. Disadvantage:The new 315-2DP cannot be a master and thus cannot have its own slaves. Dataexchange is somewhat cumbersome. 2. Let both 315-2DPs be masters and then add a DP/DP coupler as a slave on both masters. Dataexchange via i/o areas. Advantage:Both 315-2DPs can be masters. Disadvantage:Dataexchange is somewhat cumbersome. 3. Add a CP342-5 to one of the 315-2DP PLCs. Then exchange data via a configured connection and PUT/GET instructions from the 315-2DP withthe CP342-5. Advantage: More flexible. Disadvantage: The CP342-5 is expensive. Profibus Multimaster operation will slow down the Profibus network generally. Uses "connections" that may be in short supply. 4. Add a CP342-5 to one of the 315-2DP PLCs. Then exchange data via an unspecifiedconnection and PUT/GET instructions from the 315-2DP withthe CP342-5. Advantage: Most flexible. Incurs the least modifications on the "passive" 315-2DP. Disadvantage: The CP342-5 is expensive. Profibus Multimaster operation will slow down the Profibus network generally. Uses "connections" that may be in short supply. Unspecified connections puts a slightly higher CPU load on the passive 315-2DP. There are several other options. The ones with Ethernet seems most interesting.
Jesper Pedersen Posts: 279 Rating: (30)
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