Clarification on Modbus RTU over TCP

Hi I have a modbus devices connected in serial, and a gateway that converts the serial into ethernet (modbus TCP).

Below is the simplest diagram on what is my setup:

I am new to Ignition gateway, but my simple question is how am I going to read data for each of my devices, (the number of below each devices are their slave IDs).
I found these modbus RTU over TCP driver in Ignition, but I am not sure if I am configuring it right, supposed if I wanna read data on slaveID 5, should I put something like this on the local address option?

And I need to add more devices (RTU over TCP) for each slave IDs I have?
To be honest I am also not sure if I am using the right device (the RTU over TCP) or should I use the modbus TCP device for this setup?

Thanks and regards,

Hi Henjoe,
On the tag OPC path, you can specify the slave ID: [DeviceName]SlvID.PointAd

e.g. : [TEST]1.C123 for the Coiler on slave 1
Then you can use [TEST]2.C123

Information on this page: Modbus Addressing - Ignition User Manual 8.0 - Ignition Documentation (
Search for Unit ID

Hope it helps.


Thanks @Martial_Wilbert for this info!

Highly appreciated.