Ignition as Modbus slave

Morning all

I have a number of remote sites that currently run with Proface touch screens and I connect to these with a central Ignition server over 3G/GPRS.

The plan is to remove the Proface screens (we need more functionality) and replace them with a panel PC and run a lite version of Ignition. All simple.

However, for legacy reasons to need to have around 100 read only tags available, to be read over Modbus TCP, the Proface screen does this at present, and I’d like Ignition to do this but I’m not sure how. Can Ignition act as a Modbus slave? I know I could do it with a small PLC but I’d prefer not to have additional hardware and I’m tight on budget (as always)


We could build this inside a module. PM me and we can discuss details.

Hi Kyle

I’ll PM you on Monday when I’ve had a think. it might be a useful module for others

I’m sure I can do this with the Kepware OPC, I’ll test it Monday, but I was looking for somthing as part of Ignition, I was wondering if the Modbus V.2 driver had a slave option I’d missed but I presume not.


We have 40+ remote locations on Raven cell modems…what exactly are you trying to accomplish?


I need each remote instance of ignition, which will be a vision module and the SQL Bridge Module, to have a set of Modbus registers available on IP port 502 for other local systems to read. It is not feasible to change these systems at this stage.
At present the Proface screen acts a Modbus master to collect data from various devices, it has a Mitsubishi driver to collect from a PLC and has a Modbus Slave driver. It is the Modbus slave that I am trying to replicate.
I have licences for MXOPC for the Mitsubishi PLC, that OPC also has a Modbus driver but cannot act as a Modbus slave.
Kepware seems to have a slave option so I will look at that,
Of course there is always the option of installing hardware, either a little PLC or modifying the Mitsubishi PLC, I’ve found that Mitsubishi PLC and Modbus are not easy bedfellows.
I will have very limited down time at each site so I’d like to keep physical changes limited to the screen.

I have no trouble with our Digi Transport modems


Yeah, I’ll just step in to verify here, there’s no slave functionality in our Modbus driver.

I’d thought about it before, but this is the first time ever hearing anybody want to use it that way.


Thanks for the clarification


why dont you just use opcua?


I don’t understand, could you explain?


Google ‘Modbus TCP slave simulator’. There are several programs you could load on the same computers as your Ignition gateways that would be able to act as local Modbus slaves. Ignition could write to the local slave simulators and your existing Modbus masters could read from them.

I am not sure any of these are production environment ready though, but at free, the cost might be right you. This is what the Kepware Modbus slave server would do also.

I decided to go with Kepware

It took 30 seconds to set up and works like a dream, both reading and writing to from the remote master.

I have to factor in my time and travel costs if an alternative fails etc.

thanks for the help