Sense[N]:Power:unit; Sense:power:unit:all:csv; Sense[N]:Power:wavelength[:All] - Keysight N774 C Series Programming Manual

4 Measurement Operations & Settings
Command:

:SENSe[n]:POWer:UNIT?

Syntax: :SENSe[n]:POWer:UNIT?
Description: Gets the current sensor power unit of selected channel
Parameters: None
Response: An integer value:
Example: :sens1:pow:unit? → +1
Affects All power meters
Command:

:SENSe:POWer:UNIT:ALL:CSV?

Syntax: :SENSe:POWer:UNIT:ALL:CSV?
Description: Gets the current sensor power units for all channels
Parameters: None
Response:
Example: :sens:pow:unit:all:csv? → 1,0,1,1,1,1,1,1
Affects All power meters
Command:

:SENSe[n]:POWer:WAVelength[:ALL]

Syntax: :SENSe[n]:POWer:WAVelength[:ALL]<wsp><value>|MIN|MAX|DEF [PM|NM|UM|MM|M]
Description: Sets the sensor wavelength.
Frequent use of this command can conflict with the timing of autoranging in some configurations. Autorange can be disabled
before and enabled after the command if needed.
Parameters: The wavelength as a float value in meters.
Also allowed are:
88
0: Current power units are dBm.
1: Current power units are Watts.
MIN: minimum programmable value
MAX: maximum programmable value
DEF: the preset (*RST) default value
Keysight N774xC Series Multiport Power Meter Programming Guide