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Modbus TCP Topology and IPv6
What are the limitations of having Modbus TCP with another protocol in the same network, ex, intranet in an enterprise for example?


Does the Modbus TCP needs a dedicated network or can it be used in the same network with another protocol?

Is there any limitations for the Modbus TCP?


You can get free and simple source code for a Modbus TCP master here:

There is also a link there to free client software.

Sorry Stan that I didn't answer any of your questions in my previous message.

>Does the Modbus TCP needs a dedicated network or can it be
>used in the same network with another protocol?

It is standard Ethernet so it should work anywhere (unlike Ethernet/IP).

>Is there any limitations for the Modbus TCP?

There probably are, but I'm not the one to answer this question...

By James Ingraham on 11 May, 2017 - 2:32 pm

Modbus/TCP can indeed run on the same network with other protocols. It's not always a good idea, however. Without more information, it's difficult to have any recommendations, but you definitely need to think about what you're trying to accomplish and how other things might affect your Modbus/TCP traffic.

As for limitations for Modbus/TCP, there are many, but it's hard to single anything out with such a broad question. A few come to mind immediately; no more than 256 words (i.e. 512 bytes) per message, only 64K address space, not all devices support all functions, etc.

-James Ingraham
Sage Automation, Inc.

Hello and thank you both for your answers.

I should be more explicit in my questions...

Well for the network, i'm wondering if it can work with other protocols like bacnet since they're using the same interface, and maybe the enterprise intranet. (having modbus frames with print machine frames lol)

For the limitations it is more an implementation questions. i found that a master TCP can communicate with at most 16 servers simultaneously. but can't see anything else.

Talking about limitations, the max servers should be configurable between 1-16. apart from that when you using ipv4 or ipv6 we should have the same configuration right? only the address format changes (always ip address subnet mask and default gateway) followed by the timeout.

I hope it's clearer.


Modbus will work fine on a network along with BACnet and other protocols. If you think of a typical network there are all kinds of protocols and messages being transmitted back and forth between devices. As the other people mentioned there will always be limitations but in general terms you should have no problem.

Thank you!! that was helpful