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EM277 double duty MPI + Profi

Created by: Darren_T3 at: 7/23/2007 11:51 PM (3 Replies)

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7/23/2007 11:51 PM	Rate (0)
Darren_T3 Posts: 95 Rating: (10)	Howdy Folks, Can the EM277 (Profibus Module) pull MPI + Profibus double duty? Let me explain… I currently have the EM277 connected to Profibus and everything upstream is working just fine – no problems there. The spec. I am working on requires (7) TD200C’s. From my reading and understanding of the fine Siemens literature I understand that I can have 3 of these jewels connected to Port 0 of my S7-222 and the EM277 will handle 5. Well, as long as the baud rate is the same (187.5) on the EM277 can I ‘piggyback’ the TD200C over MPI and still have the Profibus connection or do I require a separate EM277 (one for Profibus duty and the other for the 4 additional TD200C’s)? I have been trying several configurations but I cant get that dog to hunt so I am wondering if it is even possible. Thanks in advance for your kind response. Cheers, Darren in (Sunny, Hot & Beautiful)Dallas
Darren_T3 Posts: 95 Rating: (10)
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7/24/2007 7:56 AM	Rate (1)
Helmut_13 Posts: 2930 Rating: (432)	Hi Darren, it is possible to use the EM277 as a DP-Slave so an DP-Master can communicate to it and at the same time you can use TD200's (Rel. V2.0 or greater) to communicate via the EM277 to a S7-200 PLC. This information you can find in the S7-200 system manual at page 430. The only thing you have to do is to set all units (DP-Master and TD's) to the same baud rate. Depending on the max. baudrate of the TD's it is 9600, 19200 or 187.5k. The EM277 does not require to set the baud rate because autobaud is supported from 9600bps to 12Mbps. I hope this helps. Regards Helmut
Helmut_13 Posts: 2930 Rating: (432)
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7/24/2007 6:04 PM	Rate (0)
Darren_T3 Posts: 95 Rating: (10)	Hi Helmut_13, Thanks for the great feedback – 5 stars from me!!! I found the reference in the manual and will certainly give it a try. I have some questions about moving the data back and forth between Profibus Master and the EM277. Our setup is a bit interesting we start off with 400H systems in redundant mode and a redundant Profibus network. I use a Y-Link to ‘merge’ the two Profibus networks to a single line and the EM277 is on the downstream side of the Y-Link. For my testing I just created a VAT in the S7-400 side and am manipulating the data that way and I can see it in the Chart of my S7-222 side and the data is moving as expected. Having said all that here are some questions: Do I have to use XPUT/XGET functions as the manual states or can I just write data to the I/O location that is designated in my Hardware Configuration on the S7-400 side and treat it as regular I/O? If the functions are required is XPUT/XGET the only communication functions I can use compared to BSEND/BRCV, USND/URCV and PUT/GET? I will need to move a 10 digit number from the 400 to the 200 and some other bits so what would be the best way to do that: Stay with the OB1 Process Image or Move higher into the Periphery area of the I/O The ultimate goal is to display the 10 digit number on one of seven TD200C’s and have some local operator interaction with the 400 program via the 222 -> EM277 -> Y-Link -> Redundant Profi -> Redundant 400H systems. So you see the 200 is kind of playing the roll of gateway to get the TD200C to communicate with the 400H’s Thanks for your thoughts and insight I greatly appreciate your feedback. Cheers, Darren in Dallas
Darren_T3 Posts: 95 Rating: (10)
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7/24/2007 10:53 PM	Rate (0)
Helmut_13 Posts: 2930 Rating: (432)	Hi Darren, have you seen this information in the Siemens Customer Support pages? http://support.automation.siemens.com/WW/view/en/2615830 As I understand XPUT/XGET and so on are not necessary. The Master directly writes/reads from the V-Memory of the S7-200 or I/O's. I hope this helps Regards Helmut
Helmut_13 Posts: 2930 Rating: (432)
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