Keithley 2750 User Manual page 68

Model 2750 Multimeter/Switch System User's Manual
If a system channel is already closed and you attempt to select the DCI or ACI function,
the message "INVALID FUNC" will be displayed briefly. For remote programming,
error -221 (Settings conflict) is generated. Example:
SYST:PRES
ROUT:CLOS (@101)
SENS:FUNC 'CURR:DC'
Close/Open Switching Module Channels
' Restores system preset defaults.
' Close system channel 101.
' Attempts to select DCI function – Generates
' error -221.
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