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interconnection between PLC

Created by: Manishkools at: 11/3/2009 12:09 PM (4 Replies)

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11/3/2009 12:09 PM	Rate (0)
Manishkools Posts: 50 Rating: (1)	Hi experts, In our plant we have one HMI for 28 s7-200 PLC they all are working ok my. but one can see that communication is not stable. several external parties have visited and every person suggest some modification in communication wiring. Is there any standard wiring method for connecting the PLC ( Port 1 of all PLC are interconnectconnected ) thanks in advance Manishkools
Manishkools Posts: 50 Rating: (1)
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11/4/2009 2:17 PM	Rate (0)
J_Bell Posts: 5822 Rating: (412)	Dear Manishkools, please excuse but I fear your information is slightly mistakable. So do you notice the problems in the communication with one or all of the 28 PLCs? You mentioned that you use one HMI connected to all 28 PLCs, how do you interconnect to the PLCs, do you use a CP Card? Which settings are being used with this interface? Ifyou use any interconnection's between the PCLs, did you notice any problems there... if it is used? Regarding your networking there might be some issues... but as I do not know how it looks like I think it would be very important to know more about it. First of all, do you use the CPU PPI interface for the interconnection? Do you use MPI or PPI? How large is the line (or do you use any other topology?) you use? (size in meter, please) Do you use any network components there, for example RS485 Repeater or OLM? Ifear there is a lot we need to know to say anything. Best regards J_Bell
J_Bell Posts: 5822 Rating: (412)
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11/4/2009 5:11 PM	Rate (0)
Lifrasil Bronze Member Joined: 9/29/2005 Last visit: 12/16/2024 Posts: 313 Rating: (24)	Hi, in case the spontaneous errors appear randomly at all 28 plc´s try to cascade the informations at your HMI. Means: Don´t try to display values from all 28 station on one screen, which means again that all implemtend connections are busy. Try to multiplex the information to several screens and use as value-updating mechanism not "100ms-always" but "100ms-when-in-use". You know what i mean i don´t know the exact name at the moment. Furthermore think about to disconnect and connect the whole PLC-connection depending on what connection you need at the moment. regards

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11/7/2009 6:17 PM	Rate (0)
Manishkools Posts: 50 Rating: (1)	Dear J_Bell Thanks for reply. sorry i was not able make myself clear. actually 18 ( not 28 my apologies) S7-200 PLCs are connected to one touch screenhaving monitoring softwarethe PLCs are distributed in around 10mtr of area the max cable length from one end to last end around 30 m. I am not aware of any of the programme of PLC of MMI. I just want to know the correct way toconnect the communication bus as most of my advisors suggesting the modification in the connections of communications like connecting shield to the earth or connecting terminator at the last node etc. i just want to know a standard procedure for connecting bus, terminators, shield etc.
Manishkools Posts: 50 Rating: (1)
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11/11/2009 12:14 PM	Rate (0)
J_Bell Posts: 5822 Rating: (412)	Hello, well, in this case I would recommend to you to use the Manual: SIMATIC NET PROFIBUS Network Manual System Manual check there especially for the appendix. Well, do not worry, you have PPI or MPI but still RS485 Bus... so the PROFIBUS information is still valid for you. For the S7-200 you only have to care that you have no potential free installation. PPI or MPI interfaces are potential bounded and so you may not exceed a segment size of 50 m. Termination has to be done actively on both ends of the line you have to use. Star topology would require expensive PROFIBUS Repeater, also for PPI / MPI. Grounding of the used shielded cable is also recommendable at each entering or leaveof a cabinet. But you better read the appendix of the manual first. Best regards J_Bell
J_Bell Posts: 5822 Rating: (412)
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