ILX Lightwave FPM-8200, User Manual

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G P I B C O M M A N D R E F E R E N C E
GPIB Command Reference
66
FPM-8200
C H A P T E R
4

Action Applies an offset to internal FPM 8200 amplifiers to eliminate fixed errors from such effects as
detector dark current and ambient light.
Notes This function is the same as the front panel ZERO button.
Before starting measurements it is good practice to first zero the meter. The concept is similar to
shorting the leads of a voltmeter and making sure the meter reads zero.
To eliminate all offsets, no light must be on the detector. A connector adaptor can be used for this
purpose, provided a patch cord is connected and the other end of the fiber is not exposed to
ambient light.
You can usually use ZERO with your test setup connected to eliminate small external effects such
as ambient room light from your measurement. However, the FPM−8200 limits the amount of offset
because large external influences are too unstable to include in measurements. Error E−531 results
when there is too much ambient light for the zero operation.
The FPM−8200 keeps the last zero setting, even when you turn power OFF. So if you zero the meter
to your test setup, be sure to zero the meter again when you are finished. It may be more conve−
nient to do this with the front panel ZERO button.
These commands will cause error E−532 if they start before ZERO completes:
Range
Range:AUTOWave Cal:User
After ZERO, you should confirm completion with ZERO?, or with OPC?. Then check the error queue
(see ERRors?) before proceeding.
During the zero process, the ZERO indicator blinks on the front panel, and the number "0" moves
across the display. When the process is complete the display shows "−LO−".
You can interrupt the zero process from the front panel even if it was initiated by GPIB by pressing
the front panel
ZERO button before it completes.
If the zero process is interrupted or was not successful, gain offsets remain unchanged.
Example ZERO˙Start the zero process.
Action Requests status of the FPM−8200 zero operation.
Response 0 = zero operation is not in progress.
1 = zero operation is in progress.
Note Since the OPC flag is held false during the zero process, zero status can also be determined by
checking OPC status. See *OPC?.
Example ZERO?˙Response 1 means the zero operation is in progress.
Zero?˙Response 0 means the zero process is not in progress. If you just issued a ZERO
command, this confirms the process is complete.
ZERO C
OMMON
D
EVICE
D
EPENDENT
F
RONT
P
ANEL
ZERO? C
OMMON
D
EVICE
D
EPENDENT
F
RONT
P
ANEL