Modbus RTU Domains Properties

Fields in the Domains dialog box are as follows:

Domain Sizing

Select one of the following.



Select this option to set the Register Size values for the domain type by reading the storage capacity available on the device.

Note: A value of 0 in a Register Size field indicates an invalid domain.



Select this option to enter relevant values into the Register Size fields below.

Skip General Reference

Check this option to deactivate General Reference elements for this device.


Domain Type

Domain Size

Register Size


Coil storage capacity.



Input register storage capacity.


Input Status

Status word size.



Holding register storage capacity.


Report Slave ID

Slave ID size.

General Reference Register Size (elements)

(1 -10)

Register storage capacity.

Note: By default, the domain sizes are set by reading from the hardware. Select Custom, above, to activate these fields for editing.

More information

MB_COMM_TIMEOUT Device Parameter.

MODBUS RTU Device Properties.

Modbus RTU device configuration.