If you just need to receive a serial string, you will want to use Generic Data mode and create a consume transaction.
You will need to decide if the string will always be the same length or if the length with vary. It it’s always the same, for example, 20 bytes, add ‘Data’. If it is not always the same, add ‘Variable Data’ and enter the max size. Also, Enable filling un-used bytes.
You can also use an delimiter to mark the end of the transaction if the scale uses one.
Follow the step-by-step example on page 21 of the User Manual.
For troubleshooting the serial network, there is info here: I have an LED 5 error on my Anybus Communicator