Alc:source:external:coupling; Alc:source:pmservo:channel; Alc:source:pmservo:increment - Keysight N5171B EXG Manual

Basic Function Commands
Power Subsystem ([:SOURce]:POWer)

:ALC:SOURce:EXTernal:COUPling

[:SOURce]:POWer:ALC:SOURce:EXTernal:COUPling <value>DB
[:SOURce]:POWer:ALC:SOURce:EXTernal:COUPling?
This command sets the external detector coupling factor. Use this command
when DIODe is the selected ALC source (Refer to the :ALC:SOURce command.)
Example
:POW:ALC:SOUR:EXT:COUP 20DB
The preceding example sets the external coupling factor to 20 dB.

:ALC:SOURce:PMServo:CHANnel

[:SOURce]:POWer:ALC:SOURce:PMServo:CHANnel A|B
[:SOURce]:POWer:ALC:SOURce:PMServo:CHANnel?
This command sets the power meter channel used for servo mode
Example
:POW:ALC:SOUR:PMS:CHAN A

:ALC:SOURce:PMServo:INCRement

[:SOURce]:POWer:ALC:SOURce:PMServo:INCRement <value>
[:SOURce]:POWer:ALC:SOURce:PMServo:INCRement?
This command sets the increment percentage of a measured power delta in the
Power Meter Servo mode. By default this value is 100%, meaning that the
system output power is adjusted by the measured value. This percentage can
be lowered to assure that no overshoot takes place – at the cost of additional
measurement/adjustment cycles. This command works in conjunction with the
STARt and STOP commands.
Example
:POW:ALC:SOUR:PMS:INCR 75
104
Supported All Models
*RST +1.60000000E+001
Range –200 to 200 dB.
Key Entry Ext Detector Coupling Factor
Supported All Models
*RST A
Range A/B
Key Entry Power Meter Channel (A|B)
Supported All Models
Keysight EXG and MXG X-Series Signal Generators SCPI Command Reference