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level2:communication_between_2_webhmis_via_internet

Communication between 2 or more WebHMIs via internet

Sometimes you need to have a connection between far systems, e.g. like in the following picture:

You might want to automatically control supply pumps depending on the water level in a far water tower or reservoir.

With the WebHMI and Level2 connectivity options it is done with ease:

Option 1. Using MQTT protocol

  1. Connect both WebHMIs to the Level2 IoT
  2. Subscribe the pump station WebHMI to the topic with level that far WebhMI publish onto the Level2 MQTT broker.

Option 2. VPN and Modbus TCP

  1. Connect both WebHMIs to Level2 and and remember remote node (reservoir side) IP address in the VPN network
  2. Turn On (Modbus TCP Server) on the water redervoir side
  3. Enable routing for pump side WebHMI to the remote peer node
  4. Create Modbus TCP connection on the pump side WebHMI using IP address from (1)

Option 1 Is preffered due to the nature of the MQTT protcol which saves traffice for communication while Modbus TCP will create constant polling process.