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Profibus noob question, linking variables.

Created by: Triodes at: 10/2/2006 1:40 PM (4 Replies)

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10/2/2006 1:40 PM	Rate (0)
Triodes Posts: 20 Rating: (1)	Hi, [:blush:] I'm new to profibus and have a question about gettingdata through to different stations. I have a master and two slaves, each PLC has a local DP network with it's onboard DP going toa couple of inverters (mm420 with DP interfaces). The three PLC's also have an additional DP station (CP342-5) which are used to link the three PLC's together. So three cabinets with a DP between them, plus each with a localDP network. The two slaves havean OP217B attached via MPI and need to send parameters to the master to set the speeds/enables on the MM420's. Right now I have a single DB assigned to contain all the data, but only one of my slaves is able to set data, the other I can enter what I want but it is not accepted by the master. Plus also myother slave does not see the changed data. What I do is: EachPLC has a DB (DB11) with the first 128 bytes being the setpoints and the second 128 bytes being the current status. The master sends the first 128 bytes, received the second 128 bytes. Slave 1 sends the first block of 64 bytes and receives the first block of 64 bytes.Slave two send the second block of 64 bytes and also receives the second bloc of 64. I use FC50 and FC51 for the RX/TX. This is a very simple (stupid?) way of doing things, but this is why I am asking here how you would normaly synch data between multiple units over Profibus. Is there a set range of addresses that are common (read/write) for all attached units? help [:P]
Triodes Posts: 20 Rating: (1)
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10/3/2006 2:08 AM	Rate (0)
Dec Gold Expert Joined: 5/19/2006 Last visit: 10/13/2025 Posts: 550 Rating: (107)	Hi, You have to check if your CPUs & CPs supports DX(Data Exchange) on Profibus and this might be an easy solution [;)] Dec

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10/4/2006 7:59 AM	Rate (0)
Triodes Posts: 20 Rating: (1)	I will check it out... thanks
Triodes Posts: 20 Rating: (1)
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10/5/2006 1:09 PM	Rate (0)
Triodes Posts: 20 Rating: (1)	There is not a lot of info in the manuals about DataExchange... Only found the Get/Put commands but no real info on how to set up communication between devices. I havea Master with address range 272 (16 bytes)and two slaves with address 320 (16 bytes). Using the PQW from the slave to the PIW on the master gives funky numbers. Tried the same address range but no difference. How is the data transported; if I send a block of 16 bytes fro the slave, will the master received these as the first 16 bytes on it's inputs?
Triodes Posts: 20 Rating: (1)
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10/5/2006 1:43 PM	Rate (0)
Wizard Diamond Expert Joined: 4/24/2006 Last visit: 12/24/2025 Posts: 9097 Rating: (1202)	Hello Triodes, When you use a CP342-5 you have to use Functions DP_send and DP_Receive. Have a look at the following link: http://support.automation.siemens.com/WW/view/en/18208090 Pay attention to issue 5. Here's an explanation about communicating. Hope this will help. Best regards, Wizard

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