Answer
After defining the ARB sequence it will automatically get started when turning on the master output.
Here is a description of an adequate SCPI sequence:
# Prepare ARB
# Choose the port to apply the next commands to
INST OUT1
# Delete last ARB definition in memory
ARBitrary:CLEAr
# Sequence information: 5 V, 1 A, 2 s, no Interpolation, 10 V, 1 A... etc...
ARBitrary:DATA 5,1,2,0,10,1,2,0,12,1,2,0
# Number of repitions (0 would be infinite)
ARBitrary:REPetitions 5
# Hold the last value
ARBitrary:BEHavior:END HOLD
# Load the data into the ARB memory
ARBitrary:LOAD
# Now start the ARB sequence
# Arm the channel with ARB (would also work to switch it on / off after main output is on
ARBitrary:STATe ON
# Activate the channel (would also work only with next command)
OUTPut:CHANnel:STATe ON
# Activating the main output will start the ARB sequence at the same time
OUTPut:STATe ON
Tested with:
HMC8042 V1.400