Siemens Sentron PAC3200/4200 devices.
Basically the mentioned devices have a Modbus-Sever On-Board which you can connect via our Modbus-Client interface.
The connection works quite well at the customer site and the devices provide quite a huge set of measurement and calculated values (update time app. > 100/200ms).
I have attached settings for a SENTRON3200 device connection:
It seems Modbus is quite a standard for these kind of devices, since other suppliers, like Janitza, KBR,.. also provide these interfaces.
I hope that is helpful to you.
BR, Eik