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Communication between Step7 and a Profibus PA device

Created by: guilhermecgs at: 3/24/2008 7:53 PM (2 Replies)

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3/24/2008 7:53 PM	Rate (0)
guilhermecgs Posts: 4 Rating: (0)	Helo, I´m trying to do the following: I need to communicate with Profibus PA devices to get status words from them and eventually send data to the device. I have a S7400 Cpu with Step 7, with a DP/PA coupler, and I don´t have Simatic PDM. So: If anyone can help me with one of these questions: 1)How do I communicate with a PA device, in order to get device status and send some data.(for example, the device http://www.astles.co.uk/001_pdf/download.php?filename=promag53_instr.pdf )(I need to use the device totalizer). 2)Is there any SFC, that does that? 3)How does it affect the bus baud rate and nodes? 4)Can anyone send me a example program, PLEASE! 5)Is there any program that simulates the device ? I dont have the device now, and I long as I know, the devices should only be arriving in the comissioning. You dont need to answer it all, any help is appreciated.
guilhermecgs Posts: 4 Rating: (0)
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3/24/2008 9:21 PM	Rate (0)
J_Bell Posts: 5822 Rating: (411)	Hello, maybe I can try to answer a view. First of all.. a S7 is only able to work as a Class 1 Master. So if you want to communicate with a PA Device you will have to add it as a DP Slave to your PLC. There is no other way... as far as I know at least. To get defined Records within theDevice you have to use the SFB 52 (ReadData Records). As you use the Coupler and not the Link you will have to use 45,45 kBit/s as the Baudrate on the PROFIBUS. Sadly I have no sample handy... but I guess you will find one. As far as I know there is also no Simulator to get a PA Device simulated... I am affraid... but maybe another member has a good idea for you. Best regards J_Bell
J_Bell Posts: 5822 Rating: (411)
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3/28/2008 7:37 PM	Rate (0)
guilhermecgs Posts: 4 Rating: (0)	Hello I ´ve found the answer thought Siemens Hotline support. When you are using a DP/PA coupler , the PA network is transparent in the point of view of the CLP. So, If your CLP connects the PA devices thought a DP/Coupler, you can use any of the SFC functions that read the diagnostics WORD from a DP device. Any PA devices in the network will look just the same as a DP device. For example, you can use SFC14 and SFC13. The address of the PA device will be the diagnostics address that you can find in the HW Configuration, after clicking in the PA device.
guilhermecgs Posts: 4 Rating: (0)
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