Although TRiLOGI has the SETLED command, it was never implemented in the hardware.
What is the interface to drive your 4 digit LED? Some LED has RS232/RS485 interface which the PLC can send data to be displayed. If your LED is just plain LED segments without driver, then you may use the PLC output to drive the LED segments if it is a common anode type. You will need current limiting resistor to limit the current to the LED. Note that in this case, each digit requires 7 or 8 (if including decimal) outputs.
You can then construct the segment pattern that correspond to each digit 0..9 by store them into a lookup table in memory and when you need to display a number, just take the corresponding output pattern to send to the outputs to drive the LED segments.
