To set a port to a specific modbus address, configure a device on the port and set the device address to the desired slave address. The DeltaV Explorer help provides step-by-step instructions for adding serial devices.
For example, the following steps describe how to configure two serial devices (a multi-port configuration) connected to port 1 of a serial card.
Select port 1 (PO1) of the serial card.
Right-click and select New Serial device.
Set the device address to match the address of the physical device connected to the serial card.
Repeat steps 1 through 3 for the second device. Set the address of the second device to match the address of the physical device connected to the serial card.