I would like to connect Multitech gateway to Proface HMI (SP5000 Series). I have sensors data streaming to my Node-RED online app through Multitech gateway. I would like to forward these data to Proface HMI device. Could you suggest me the best way to resolve this issue?
Assuming the Proface HMI (SP5000 Series) supports modbus IP then that would be the way to do it.
However, your main problem is MT GW runs an old version of Node-RED
This is down't to a hardware limitation which means you can't install any of the custom modbus nodes as they won't run.
You could considered an intermediate device like Raspberry PI running NR to bridge the two devices.
Or wait for the new 64 bit GW which will available in the next few months.
The new GW will allow you to install modbus IP, or even some PLC drivers like S7/AB.