Modbus TCP

[meihk]

Hi, I'm trying to write a Modbus TCP Server program to connect to a device (Modbus TCP Client).

I've found this tutorial: https://knowledge.ni.com/KnowledgeArticleDetails?id=kA03q000000x0QgCAI&l=en-US 

In section "Creating a Modbus Master I/O Server", step 3 mentions that I have to choose New->I/O Server, and select "Modbus" in step 4.

The problem is, in step 4, there is not any choice. (screenshot below)

Can you tell me if I have to download any package to solve this?

Also, I think there is another way to config Modbus TCP Server that using Modbus Library. What is the difference between these 2 ways?

Thank you

[Jacobson-ni]

I believe the Modbus I/O Server is a dependency of the DSC module or the Real-Time module (though RT module only gives this option under an RT target I believe).

Both of those are paid modules and DSC requires a deployment license so I usually just recommend downloading the NI Modbus Library off of VIPM which is free. The Modbus I/O server basically lets you configure a connection and access coils/registers though shared variable nodes while the Modbus API operates as a pretty standard LabVIEW library. Personally, I think Modbus is a simple enough protocol that using something like an I/O server doesn't significantly simplify the programming process but does significantly reduce the ability to debug any potential issues which is why I usually try to avoid it.

[meihk]

Hi Jacobson,

Thank you for replying.

Through your suggestion, I guest I will choose to use Modbus Library instead of I/O Server in DSC module. 

But for further use, can you give me an instruction with the problem: there is no I/O Server Types? Should I install anything else to add a Modbus I/O server or some types like that?