Model 6220/6221 User’s Manual DC Current Source Operation 3-11
Return to Section 3 topics
Autorange
Front panel operation
The AUTO range key is a single action control to select the best fixed range for
the displayed source value. After setting a source value, pressing AUTO will
ensure that the best fixed range is selected.
For example, assume the source is set to +1mA on the 20mA range (+01.000 mA
displayed). When the AUTO key is pressed, the range will change to the 2mA
range (which is the best range).
Autorange is only asserted (enabled) for the instant that the AUTO key is pressed.
Therefore, the AUTO annunciator does not turn on. If already on the best range,
pressing AUTO will result in no action.
Remote operation
For remote operation, autorange remains active when it is enabled. When the
source value is changed, the range will (if needed) automatically change to the
best range for that value. With auto range enabled, the AUTO annunciator turns
on to indicate that autorange is active.
For example, assume autorange is enabled, and the source is presently set for
1mA on the 1mA range. When the source value is changed to 5mA, the range will
automatically uprange to the 10mA range.
Active autorange will disable if a command to select a fixed range is sent. The
commands to control autorange and select a fixed range are listed in Table 3-2.
NOTE Active autorange is only intended for remote operation.
When the Model 622x is taken out of remote (e.g., LOCAL
key pressed), the AUTO annunciator stays on and auto-
matic down-ranging remains active. Active autorange
will disable (AUTO annunciator turns off) when a RANGE
or
key is pressed.