IEEE-488 Reference
3-97
overflowed ("OFLO") or a reading has not been triggered ("----"), an error occurs when this
command is sent.
The :ACQuire command is coupled to the :REFerence <n> command. See the description for
:REFerence for details.
3.19.8
:IREFerence <b>
[:SENSe[1]]:RESistance:IREFerence <b>
Control amps reference
Parameters
<b> =
ON or 1
Enable amps reference for ohms
OFF or 0
Disable amps reference for ohms
Query
:IREFerence?
Query state of amps reference for ohms
Description
This command allows you to use an established amps reference for the resistance measurement.
When an amps reference is established (see paragraph 3.19.7) and this command is used to en-
able the amps reference for ohms, the current value used to compute resistance (Iohm) is the
algebraic difference between the input current and the reference:
I
ohm
= I
input
- I
reference
Resistance (R) is then computed using I
ohm
and the V-Source output (V).
R = V/I
ohm
Typically, amps reference represents the leakage current in a test fixture. Thus, this command
allows you to eliminate this leakage current for the resistance calculation.
3.19.9
:DIGits <n>
[:SENSe[1]]:VOLTage[:DC]:DIGits <n>
Specify resolution; Volts
[:SENSe[1]]:CURRent[:DC]:DIGits <n>
Specify resolution; Amps
[:SENSe[1]:RESistance:DIGits <n>
Specify resolution; Ohms
[:SENSe[1]]:CHARge:DIGits <n>
Specify resolution; Coulombs
Parameters
<n> = 4
3.5 digits
5
4.5 digits
6
5.5 digits
7 6.5
digits
DEFault
6 (5.5 digits)
MINimum
4 (3.5 digits)
MAXimum
7 (6.5 digits}
Query
:DIGits?
Query selected resolution
:DIGits? DEFault
Query *RST default resolution
:DIGits? MINimum
Query minimum allowable resolution
:DIGits? MAXimum
Query maximum allowable resolution
Description
These commands are used to select display resolution for the specified measurement function.
Even though the parameters for this command are expressed as integers (4 to 7), you can specify
resolution using real numbers. For example, to select 3H digit resolution let <n> = 3.5, for 4Hd
let <n> = 4.5, and so on. Internally, the instrument rounds the entered parameter value to the
nearest integer.
