Modbus master sessions

edge
#1

Hello, thanks for creating a post :slight_smile:

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#2

Hi,

How many modbus sessions can handled by Edge Modbus master per second?

is there any limit for modbus master to connect slaves(actual limit is 247)?

Thanks,
Chandra.

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unlisted #3
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#6

So @Chandhu_Dangudubiyya, I did some research for you and here is what I discovered:

While Modbus RTU is limited to 247 slaves. The Modbus/TCP protocol itself has no limit for the number of slaves (source: here and here).

So, this means that the limitation for the Edge Agent, which is serving as the Modbus TCP client (or Modbus Master), is a software and hardware limit.

In terms of software, the only limit is a workflow timeout. Edge Workflows have a timeout of 60 sections. The Modbus Node will open and close the TCP per node. The limit would be the number of TCP connections you can open/close within 60 seconds, which brings us to the hardware limit.

Since Edge Workflows run on gateway hardware you can define, how quickly and how many workflows the Edge Agent can run is directly tied to the resources (CPU, memory, etc.) on the Gateway.

To sum things up, there no define limits here for the Edge Agent; it’s dependent on your environment. All things considered, you should be able to make many connections using an average gateway. As far as we know, no one has hit any limit yet. If you do, let us know and we’d be happy to help resolve.

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