How to read S7-300 PLC using C#

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Hi Experts,

I am beginner in PLC and C#. Can you guide me or provide sample code to connect and read data from PLC. (example- PLC db2.real16 or db2.dbd16 tags)

Thanks

Posted 31-Dec-15 17:10pm

Member 12109707

Updated 14-Mar-17 14:16pm

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User 59241 · Answer 1 · 2015-12-31T17:22:00

Solution 1

As a beginner the best thing to learn right now (before anything else) is how to use Google. For example: Google[^]

and my gosh right near the top of the results is CP:PLC Communication Using .NET[^]

Also look at: C# Corner : Error Display[^]

Posted 31-Dec-15 17:22pm

User 59241

Updated 31-Dec-15 17:36pm

v2

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Member 12109707 31-Dec-15 23:31pm

I checked the same earlier also but need one more help about the same.

Where I have to put value like (db2.real16) or any conversion required.

Dim cmd As String
cmd = ""
cmd = cmd & "5000" ' sub head (not change)
cmd = cmd & "00" ' network number (not change)
cmd = cmd & "FF" ' PLC number (not change)
cmd = cmd & "03FF" ' I/O number (not change)
cmd = cmd & "00" ' (not change)
cmd = cmd & "0018" ' length of demand data (change)
cmd = cmd & "000A" ' CPU INSPECTOR DATA
cmd = cmd & "0401" ' READ COMMAND
cmd = cmd & "0000" ' SUB COMMAND
cmd = cmd & "D*" ' DEVICE CODE
cmd = cmd & "009500" '"010000" 'adBase ' BASE ADDRESS
cmd = cmd & "00022"

[no name] 31-Dec-15 23:38pm

Spend some time and do some background reading. You need to understand the basics. There are many examples available. Taking a scattergun approach is not the way.

Richard MacCutchan 1-Jan-16 5:16am

Your main problem is that you are using VB rather than C#.

Per Söderlund 2-Jan-16 3:56am

Didnt you say you want to connect to a S7 PLC?
Arent you building a buffer from an example that connects to a mitsubishi MELSEC PLC?
That will never work because they have their own protocols, there is no standard that works for all.

Per Söderlund · Answer 2 · 2016-01-01T21:53:00

Direct connection between PLC and client application is not recommended.
Most PLCs only allow one connection to be established.

Usually one uses an "OPC Server" as middleware to handle multiple clients.
Google for an OPC Server that supports your PLC.
If you are using C# you can search for Graybox OPCDA wrapper which you can use to connect to OPC in a safe and easy way (you also need the native OPCDA dll).

If you do choose to connect straight to PLC, you have to know that the communicationsprotocol is different for every PLC (Siemens,Mitsubishi etc). The PLC have to be set to either text or binary format and you have to translate it manually.
Sometimes there is a networkscard in PLC that have it own communicationsprotocol.

Basically what I´m saying is. Use an OPC Server or work your ass off trying to configure PLC with components and hacking the communications buffer because documentation is almost never right.

hovnlu · Answer 3 · 2017-09-02T23:57:00

Solution 5

S7.Net Tutorial with C#
https://www.youtube.com/watch?v=nSnGKm3FSbk&list=PLRCEJ0bGSS1ZlU34IXsIKS62IHH5FcgU1

<iframe width="560" height="315" src="https://www.youtube.com/embed/nSnGKm3FSbk" frameborder="0" allowfullscreen></iframe>

Posted 2-Sep-17 23:57pm

hovnlu

Updated 3-Sep-17 0:35am

Comments

OriginalGriff 3-Sep-17 6:40am

I'm going to let this through, because it is relevant - but ...
1) Try not to post YouTube links - they will normally get caught by the spam detector.
2) Please try to avoid posting solutions to old questions - and this one is over a year and a half old, with solutions - as it's unlikely the original poster is still working on the problem and you do look like a rep point farmer, which is counted as abuse.

In this case I think you were genuinely trying to be helpful, so I let the answer through and won't assume you are farming rep points! But there are some trigger-happy users out there, so please try to stick to more recent questions in future to avoid them assuming you are an abuser and starting the "kick him off the site" process.