3-18
Measurements and Sourcing Voltage
Model 6487 Reference Manual
Operate considerations
OPER (operate) key
The OPER (operate) key will function to turn the voltage source off, even if the instrument
is operating under remote control (REM annunciator on), assuming that the LLO (Local
Lockout) function has not been employed. While in remote, the OPER key will only turn
the source off. To turn it on, the Model 6487 must be in local (see
).
Voltage source off state
The voltage source is not in a high-impedance state when it is turned off. Rather, it is in a
state that acts just like the voltage source was programmed to 0V on the selected range. It
will enter this state on power-up after the VOLTAGE SOURCE OPERATE light blinks. In
contrast, the safety interlock
will
cause the voltage source to go into a high-impedance
state instead of 0V output and the source will stay in the high-impedance state until the
operate state is changed to on. The exception is the 10V range where the interlock is
optional. The OPERATE light and front panel display do not indicate the difference
between 0V output and high-impedance output caused by an open interlock. The interlock
status is available by query via remote (see
).
Compliance indication
At any time, it is possible that the voltage source will go into compliance (current limit
reached). Should this situation occur, the OCOMP annunciator (Output Compliance) will
flash and the displayed voltage value for readings of less than 6 digits will alternate
between showing the value and displaying “CMPL”. If you are in a menu where the volt-
age source value is not shown on the right-most four characters of the display, only the
flashing OCOMP annunciator will be shown.
Open interlock indication
If the interlock is asserted (opened) while the unit is on 50 or 500V range, the voltage
source will also technically be in compliance. However, there will be no indication of that
status over the front panel or in the status registers (
). The open interlock takes
precedence.
