Some TSP code and results to check this:

dmm.measure.autozero.enable = dmm.OFF
dmm.measure.count = 2
for i = 1, 10, 1 do
dmm.measure.nplc = i
dmm.measure.read()
diff = defbuffer1.relativetimestamps[defbuffer1.n] - defbuffer1.relativetimestamps[defbuffer1.n-1]
diff = diff*1000
print("sample period ="..16.67*i.." , actual time = "..diff.."nplc = "..i)
end

sample period =16.67 , actual time =16.706666 nplc =1

sample period =33.34 , actual time =33.368485 nplc =2

sample period =50.01 , actual time =50.038273 nplc =3

sample period =66.68 , actual time =66.703666 nplc =4

sample period =83.35 , actual time =83.374394 nplc =5

sample period =100.02 , actual time =100.037848 nplc =6

sample period =116.69 , actual time =116.704788 nplc =7

sample period =133.36 , actual time =133.37103 nplc =8

sample period =150.03 , actual time =150.036636 nplc =9

sample period =166.7 , actual time =166.704273 nplc =10

dmm.measure.autozero.enable = dmm.ON
dmm.measure.count = 2
for i = 1, 10, 1 do
dmm.measure.nplc = i
dmm.measure.read()
diff = defbuffer1.relativetimestamps[defbuffer1.n] - defbuffer1.relativetimestamps[defbuffer1.n-1]
diff = diff*1000
print("sample period ="..16.67*i.." , actual time = "..diff.."nplc = "..i)
end

sample period =16.67 , actual time =16.707213 nplc =1

sample period =33.34 , actual time =33.373909 nplc =2

sample period =50.01 , actual time =50.040182 nplc =3

sample period =66.68 , actual time =66.704819 nplc =4

sample period =83.35 , actual time =168.76 nplc =5

sample period =100.02 , actual time =202.091 nplc =6

sample period =116.69 , actual time =235.426 nplc =7

sample period =133.36 , actual time =268.759 nplc =8

sample period =150.03 , actual time =302.093 nplc =9

sample period =166.7 , actual time =335.427 nplc =10