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Old September 18th, 2015, 11:19 AM   #1
Pete_S
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Unhappy Siemens S7-300 MPI to OPC server connection

Hello All,

I am having trouble setting up a S7-300 MPI connection using Simatic Manager 5.5. I am trying to use an OPC server with a S7 MPI driver to read data from the PLC. I have an S7-300 that has a valid MPI connection configuration but that controller does not have any data blocks configured. After too much time beating my head against my desk I decided to reach out for help. Can someone help me with steps required to pull running configuration on MPI configured PLC into Simatic manager so I can add a add a data block or configure from the ground up? I have experience with AB, GE and DirectSoft products but Siemens is really giving me a run for my money. Thanks!
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Old September 18th, 2015, 02:57 PM   #2
Thomas_v2
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Hi,

you can first try to read marker/flag values. They are always there, even without any program in the plc.
The basic setup for accessing a S7 via MPI is the MPI address of the CPU and the rack/slot combination. This is the position of the CPU in the S7 rack. A S7-300 has always a rack/slot combination of 0/2. With a S7-400 there are other combinations possible, as you can place the CPU on a position you want, or you can have multiple CPUs is one rack.

Who is the vendor of your OPC server? The item namings differ always a little bit between them.
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Old September 18th, 2015, 03:25 PM   #3
Pete_S
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Quote:
Originally Posted by Thomas_v2 View Post
Hi,

you can first try to read marker/flag values. They are always there, even without any program in the plc.
The basic setup for accessing a S7 via MPI is the MPI address of the CPU and the rack/slot combination. This is the position of the CPU in the S7 rack. A S7-300 has always a rack/slot combination of 0/2. With a S7-400 there are other combinations possible, as you can place the CPU on a position you want, or you can have multiple CPUs is one rack.

Who is the vendor of your OPC server? The item namings differ always a little bit between them.
Hi Thomas_v2,

Thanks for your swift reply. I am trying to resolve an issue with Proficy OPC server running on a Quickpanel+ where floats in a data block can not be read. I have successfully created a project from scratch for my CPU315-2 PN/DP controller that has a data block with a few floats in it. I can successfully connect to controller using Kepware S7-300 Ethernet driver and read/write to floats in my data block. However when I connect null modem serial cable to MPI adapter and Quickpanel+ I am not able to get good quality on any known tags such my DB floats or other generic registers as you referenced.
I am confident that I am missing something in my object configuration in Step 7 as I have an older CPU315-2 DP controller that the MPI was originally connected to with a program running and I am able to connect the Proficy server running on the panel and connect to known registers, but no data blocks are on that controller and I don't have backup for that controller.
So I see 2 ways to resolve, and I am stuck on both:
1: find the MPI configuration "gotcha" in my CPU315-2 PN/DP config so I can connect to the server on the panel
2: find a way to preform blind upload from CPU315-2 DP controller. When i set PN/PG interface to either PC (auto) or PC (MPI) and attempt to upload I get an error that the connection link can not be configured or is broken respectively. That controller does not have an Ethernet port, and although I have a Simatic NET 343 module in the rack it appears that it is not possible to upload from that module.
Any advice would be greatly appreciated!
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Old September 18th, 2015, 03:39 PM   #4
Thomas_v2
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Maybe someone has changed the MPI baudrate, for any reason.
The default baudrate is 187.5 kbit/s. I would try all available baudrates, and use the "show reachable partners" dialog from the Step 7 manager, as it should show you the CPU even if it has a different MPI address as configured.
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