Skip to Content

Register Login

Industry Online Support

Technical Forum

Navigation

MPI Master Communication

Created by: a_amer at: 9/20/2008 10:52 AM (6 Replies)

Rating (0)

Thanks 0

7 Entries

9/20/2008 10:52 AM	Rate (0)
a_amer Posts: 9 Rating: (0)	Dear All, I have three S7-300 PLCs each one has its own HMI (TP227) connected over MPI interface, the three PLC are working separately. Now we need to adda remote SCADA system over MPI network to monitoring the status of all PLC plus the existing TPs :-1- Is the MPI network supports more then one master ?2- What is the max. distance allowed without repeater to connect the PLCs and the SCADA
a_amer Posts: 9 Rating: (0)
Suggestion To thank Quote Answer

9/20/2008 11:14 AM	Rate (0)
not_my_fault Bronze Member Joined: 6/13/2006 Last visit: 9/17/2024 Posts: 123 Rating: (28)	Hi a_amer, it is possible to have more than one master on a MPI network. For maximum segment-length of a MPI network see http://support.automation.siemens.com/WW/view/en/12907719 not_my_fault

Suggestion To thank Quote Answer

9/20/2008 12:33 PM	Rate (0)
Bilal Moolla Posts: 133 Rating: (9)	Hi The maximum line length in an MPI subnetwork is 50m for a baud rate of up to 187.5 Kbaud with non-isolated interfaces. Between nodes with isolated MPI interface the line length of a segment can be up to a maximum of 1000m, provided the transmission rate of 187.5Kbaud. Cheerz
Bilal Moolla Posts: 133 Rating: (9)
Suggestion To thank Quote Answer

9/20/2008 2:35 PM	Rate (0)
a_amer Posts: 9 Rating: (0)	Hi Cheerz What is the part no. of the isolated interface to extend my net to 1000 m A_amer
a_amer Posts: 9 Rating: (0)
Suggestion To thank Quote Answer

9/20/2008 3:38 PM	Rate (0)
dchartier Grandmaster-Expert Joined: 9/27/2006 Last visit: 1/21/2025 Posts: 12330 Rating: (2702)	Hello a_amer; The name of this interface is "RS-485 repeater", and the Siemens part number is 6ES7972-0AA01-0XA0. However, there is a particularity when using these units on an MPI network: the MPI ports on the CPUs are not galvanically isolated, whereas the ports on the repeater (basically a Profibus-DP unit) are. So between 2 repeaters you can extend up to 1000m at 187,5 kB, but only 50 m between MPI ports of the CPUs. So: if there is nothing but cable between 2 repeaters, MPI can go up to 1000m. But between 2 MPI ports or between a CPU MPI port and a repeater, the maxmum is only 50 m. The attached diagrams can perhaps explain more clearly. Hope this helps, Daniel Chartier Edit: Sorry Bilal, I had notread your previous post, it looks like I am late in replying. D.C. Attachment MPI_Repeater.JPG (378 Downloads)
	Last edited by: dchartier at: 9/20/2008 3:45 PM
Suggestion To thank Quote Answer

9/21/2008 1:07 PM	Rate (0)
Bilal Moolla Posts: 133 Rating: (9)	Hi D.C No worries . Your reply was much better with the Layout drawing. Cheers.
Bilal Moolla Posts: 133 Rating: (9)
Suggestion To thank Quote Answer

9/28/2008 10:36 AM	Rate (0)
Ayman Elotaify Platinum Member Joined: 5/28/2008 Last visit: 1/21/2025 Posts: 4518 Rating: (841)	Hi a_amer, Communication with MPI network can be done easly. You have to dedecate a single network for the three PLCs and the three TP(s) and the master station. Keep in mind that each station should have a uniqueMPIaddress. It's easy and it it something like profibus communication but it is limited to 157.5 kBps. Also. there is something and I think it may be useful for you and the others. To useGDC (i.e. Global Data Communication) for communication between CPUs and each others via MPI communication. You can connect the three S7-300 PLCs together within the MPI network and then identify the required data to be transmitted via the GDC. NB. The data can be transmitted in a data backets and it is limited in S7-300 to only 22 bytes! For example in S7-400 it is limited to54 bytes! You can see in the technical specification of the CPU, item global data communication. How to configure the GD buckets, see the attachmed screen shots. Regards, Attachment GDC.zip (364 Downloads)
	Ayman Elotaify
Suggestion To thank Quote Answer

|

Share this page:

Share this page on...

Follow us on