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N6705B Remote Current Meas Accuracy

Question asked by jbeattie on May 13, 2015
I'm trying to read the current of my N6781A (SMU) module fitted in the N6705B MainFrame. 
I'm using  "+MEAS:CURR? 4+" and the main problem is that i see a discrepancy between what the front panel says, and the returned response from my query. 
For example, in voltage priority mode with the sense set to 4-wire:

Without 4-wire sense cables, 5v output the panel reads 478.6xxuA. An ammeter in cct reads 0.47865mA and my call to "+MEAS:CURR? 4+" returns  0.48191mA.
With 4-wire sense cables, 5v ouput the panel reads 497.5xxuA, An ammeter in cct reads 0.47852mA and my call to "+MEAS:CURR? 4+" returns  0.0.4790mA.

Without 4-wire sense cables,  1.8v output the panel reads 172.3xxuA. An ammeter in cct reads 0.17231mA and my call to "+MEAS:CURR? 4+" returns  0.17501mA.
With 4-wire sense cables, 1.8v ouput the panel reads 179.1XXuA, An ammeter in cct reads 0.17228mA and my call to "MEAS:CURR? 4" returns  0.18448mA.

My query is whether this is the expected accuracy? 
I was expecting more accuracy/consistency than this from the SMU module. 
Is there a known discrepancy between the front panel reading and the remote reading? 

Many thanks.

Edited by: JBeattie on May 13, 2015 11:45 AM
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