Point-to-Point communication between two S7-300.
Created by: Tomy Master at: 11/28/2017 7:51 PM (18 Replies)
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| 11/28/2017 8:09 PM | |
Joined: 9/27/2006 Last visit: 3/27/2025 Posts: 12344 Rating:
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Hello Tomy; This document contains a sample project for S7-300 data exchanges over MPI, using X_Put and X_Get functions: https://support.industry.siemens.com/cs/ww/en/view/747743 And this discussion points to many links on the subject: Hope this helps, |
Last edited by: Jen_Moderator at: 11/29/2017 1:34:57 PMInserted right link. |
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| 11/28/2017 9:32 PM | |
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Posts: 103 Rating:
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Make it easy for yourself: get a profibus connector.
Something like the picture makes it possible for you to connect the HMI or the programming cable when you need it (DB9 facing us). The red switch connects the terminator resistors when at the two ends of the bus. Standard Profibus cable can be used, two can be connected from the bottom. Follow the directions for Profibus even when using MPI. This works very easy. So also does the GET and PUT. |
Last edited by: CJ4 at: 11/28/2017 9:34:28 PM |
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| 11/28/2017 11:31 PM | |
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Joined: 9/27/2006 Last visit: 3/27/2025 Posts: 12344 Rating:
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Hello Tomy; First I can suggest you look at this (old) document on Simens communication links, chapter 7 is dedicated to MPI communications: Communication with SIMATIC - Industry Support Siemens Next, a few details (missing in the document): MPI is a subset of Profibus, based on RS-485 standards, which is why Profibus cable and connectors are often suggested to connect the CPUs. However a straight cable connecting pins 3, 8 and 5 (GND) on Sub-D 9-pin connectors will work well for distances up to ±15m. Longer distances require a termination. Even though it is based on RS-485, distances covered by MPI are limited by the fact that the MPI ports are non-isolated (they have less power). A segment for MPI covers only 50m, for 31 nodes max; further distances can be reached by using a repeater (same a s Profibus) but other segments are only 50m long. One exception: if you connect 2 repeaters without any nodes (an empty segment), that segment can be as long as 1000m (repeater ports are isolated). An old sketch I prepared explains this, as shown below. Hope this helps, Daniel Chartier |
| 11/29/2017 2:20 PM | |
Joined: 4/28/2015 Last visit: 3/26/2025 Posts: 10837 Rating:
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Hello, maybe also this topic can help you, it's TIA prj but system can be same. In NetPro you can need both CPUs connected to MPI network, different MPI addresses and same comm speed I expect you have defined (link): MPI X_PUT/GET |
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With best regards... |
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| 11/29/2017 11:21 PM | |
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Joined: 9/27/2006 Last visit: 3/27/2025 Posts: 12344 Rating:
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Hello Tomy; Along with Duris_I's sample project, you could also have a look at this one: https://support.industry.siemens.com/cs/ww/en/view/20989875 Hope this helps, |
Last edited by: Jen_Moderator at: 11/30/2017 10:42:43 AMInserted right link. |
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| 12/11/2017 2:53 PM | |
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Joined: 9/27/2006 Last visit: 3/27/2025 Posts: 12344 Rating:
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Hello Tomy; Are you using an edge trigger on the REQ signal? Hope this helps, Daniel Chartier |
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