The OP-960+ operator panel has two voltage free contacts, both of which are solid state relays.

Wire the +pos from the PLC input to pin 3, and the return to Pin 4. Then set the function of the output 1.

If the output is required to be closed above a set weight, then set as follows:

1. Output 1 function to "Overweight"

1. Output 1 Contact to "Norm Open"

The only other thing is to set is the overweight value under the "Scale" menu.  This is the value that the output will operate at.