communication with S7-300 using Ethernet

[Thang Nguyen]

Hi,

I have a project working with S7-300 PLC of Siemens. The requirement is reading out data inside the PLC using Ethernet. After doing some research I have the 2 options: Modbus TCP/IP and OPC server. The price of modbus TCP/IP for PLC is about $3,500.00 and the price for OPC is about $550.00. This is the reason I choose OPC protocal for this project.

With OPC server, I have two options: shared variable and data socket.

I have still not worked with both of them, so I don't have any experience about it.

Do you have any recommend for em, which one I should use?

Thank you so much,

Thang Nguyen

[David Wisti]

Just wondering, how are you going to get the S7-300 to communicate Modbus TCP? Were you going to use the Siemens FB OPEN MODBUS / TCP Library?

(2XV9450-1MB00-0YE0)

I have used datasockets in the past only because it was well before shared varibles were created (Lv7.0). If a shared variables can be an OPC client without the DSC module, I would go that route. Shared variables seem much simpler than datasockets but I have never connected them to an OPC server.

[Thang Nguyen]

QUOTE(dwisti @ Apr 30 2007, 06:01 PM)

Just wondering, how are you going to get the S7-300 to communicate Modbus TCP? Were you going to use the Siemens FB OPEN MODBUS / TCP Library?

(2XV9450-1MB00-0YE0)

Thank you for your answer.

You are right, I intend to use the MODBUS/TCP 2XV9 450-1MB00

[i2dx]

QUOTE(Thang Nguyen @ Apr 30 2007, 11:57 PM)

Do you have any recommend for em, which one I should use?

I don't really have a recommendation, because I only had one project at all where I had to communicate with a SPS, but I used LV 7.1.1 and a OPC Server with DATASOCKET and it worked fine. This combination is fast enough and reliable, so if I had to do this again, I'd use OPC/Datasocket again ...

I encountered a bug in the Datasocket VIs of LV 7.1: I was not able to keep more than 5 Writing Datasocket connecitons open simultanously, because then LV crashed and frezed the PC. But when I was working with datasocket attatched controls I had no problems at all.

The reason why I was trying to keep the connections open simultanously was, that the initialisation was rather slow (about one second ...)

[Thang Nguyen]

Hi,

Do you know any LabVIEW driver for S7-300?

[i2dx]

QUOTE(Thang Nguyen @ May 1 2007, 04:42 PM)

Hi,

Do you know any LabVIEW driver for S7-300?

no, sorry ...

[David Wisti]

QUOTE(Thang Nguyen @ May 1 2007, 10:42 AM)

Hi,

Do you know any LabVIEW driver for S7-300?

The only open-source way I know is http://libnodave.sourceforge.net/index.php' target="_blank">libnodave. You might be able to use the win32 dll with Labview.

[Karl Rony]

I wasn't pleased with the performance of LabVIEW's standard OPC client capabilities in version 7.1. I didn't want to use the DSC module either. I went with www.opcware.com. I haven't tested LabVIEW 8.2's standard OPC client capabilities yet.