Skip to main content
Version: 5.1.0.0

Modbus Listener

Description​

The Modbus Listener is an Inbound Channel providing data read support utilizing Modbus technologies. The client connection to a server setup is configured in a reusable Modbus Client Configuration Landscape entry. The structure of the read data is specified in a Modbus Message Type instance.

Create a new Modbus Listener​

To create a Modbus Listener, channel follow the steps described in the general description of Channels

designer_ee_modbus_listener_create.png

Configuration​

designer_ee_modbus_listener_edit.png

  • Modbus client environment entry is a selection of one of the existing Modbus Client Configuration Landscape entries.

  • Message type is a Modbus-specific data format needs to be selected after it was imported.

  • If Register optimization is selected then the Modbus registers are combined into one batch if they are sequential and without address gaps in between.

  • A batch block is combined up to the Maximum optimization data size for register optimization. The number can usually (by the nature of the protocol) not be higher than 250.

  • The Unit ID permits entering the server identifier to be targeted by the client configuration.

Timed polling

  • Listen mode configures when the notifications are triggered.

  • Polling period configures the timing parameter of the listener.

Listen modeDescription
Start when memory changesThe data is read for every event triggered as configured by the periodic settings.
Listen for changed toggle valueValue of one register on the Modbus as specified by the message type is monitored but only creates a new message if the value is the same as the one given in the field labeled Compare to. After reading all the data the register value is set to the one given in the field labeled Write.
Read values on every polling eventThe data on the Modbus as specified by the message type is monitored but only if the data actually differs from the previously read one a message will be created.
Read only changed memoryThe listener checks for changes in the Modbus date and is only triggered if changes are discovered. The listener searches only for the values from the message type section but only values that changed in comparison to the previous read are added to the resulting message.
  • Toggle field name refers to a Modbus register (usually a coil or holding register).