PNUM = 0x06 or 0x07 for standard red respectively green LED at IQRF (DC)TR module.
Please note that the LP [N] regularly enters a sleep mode in LP-RX mode when waiting for a packet so the LEDs are switched off. To keep the LED on for some time use LED request together with IO Set request with a delay. Both requests can be stored in one Batch request so the packet will not be received after the LED command.