OPC - packages to buy

[pawhan11]

Hello.

So far I have been using RS232 to talk with PLC like siemens. It works good bot takes too much time to develop. OPC seems to be easier because I don't care about communication.

So If I want to use OPC from NI what do I need to buy? I was reading descriptions but that's not clear for me.

So far I need:

1. NI OPC SERVERS

This will take care of communication with any kind of PLC listed here: https://www.ni.com/en/support/documentation/supplemental/07/supported-device---driver-plug-in-list-f... ?

What it means that I can have , 1 Simultaneous Driver Usage or Unilimted?

2.Dataloging and Supervisory Control Module - this allows labview to talk and exchange data with OPC ?

https://www.ni.com/en-us/shop/product/labview-datalogging-and-supervisory-control-module.html

3. DSC Run-Time system

LabVIEW DSC Module Run-Time System for Windows - what is that for??

Having all of that can I compile and deploy exe that will talk with plc via opc??

 

[ValkoA]

Dear Pawhan,

There is a webcast that explains the difference between OPC Servers and the DSC Module available here, as well as a whitepaper here. With OPC Server you can indeed either communicate with one type of PLC at a time (you can use multiple PLCs, they just have to be the same type using the same driver), or multiple types, depending on the license type. 

The DSC Run-Time license is needed on machines that have no development environment, and have an executable using the DSC module deployed. 

Regards:

[pawhan11]

What about datasockets?

Can I use them in efficient way to communicate in both ways with OPC without using DSC Module?

[Dave_Brandt]

Labview can use front panel bindings to any OPC server or data socket, The datasocket uses the OPC URL path. You can create code to do this dynamically at start up. I use the tip strip to make this connection to an OPC server. This also allows you to reference the control to the plc tag/point when running or when you create an exe from your vi. 

https://decibel.ni.com/content/docs/DOC-8086

[rolfk]

Datasocket works but has the drawback that is operates synchronously. If your OPC server is slow or doesn't react for some time then this datasocket read will block that part of your diagram completely. Not a problem if you only communicate with a few OPC items but definitely not scalable to larger systems. The DSC OPC client interface uses OPC advise to read values where the OPC servers push item values to the DSC engine whenever they have a new value to report. An OPC server being slow or not reacting won't delay the update of other OPC server items.

[smithd]

Datasockets also run in the UI thread which causes problems with your application if, for example, your user opens a tools or file menu. It's a great API in theory but I wouldn't recommend it in practice.