225 Series User’s Manual
10
118120-001-Rev. A
SRQ
Service request status of GPIB
OVLD Output
overload
indicator
TRPD
Output trip indicator
VOLTS Illuminated
when
the meter is displaying
the output current.
mA
Illuminated when the meter is displaying the
output current.
4.2 PROGRAM
CONTROL
SWITCH
The front panel controls of the unit are only functional
for programming purposes when the unit’s rear panel
PROGRAM CONTROL switch (S101) is in the
LOCAL/IEEE-488 position. However, if the unit
receives a voltage programming command while S101 is
in the Remote Analog position, the switching of S101 to
its LOCAL/IEEE-488 position afterwards will then cause
the value of that programming command to take effect.
4.3 LOCAL
OPERATION
The local mode of the 225 Series provides all of the
control and monitoring functions available with GPIB
control. An SRQ may occur with no controller
connected to the IEEE-488 connector port (J9). The
SRQ front panel LED will illuminate and stay
illuminated, but this is of no concern when in the Local
mode. Any unanswered SRQ will not affect local
control in any way and the illuminated LED may be
safely ignored.
When the unit is in remote control via the GPIB, the user
must press the LOCAL/FUNCTION pushbutton on the
front panel to enter the Local mode. If the remote
(RMT) LED is not illuminated, then the unit is in the
Local mode.
If the user chooses, the unit can be programmed from the
GPIB to receive programming information only from the
GPIB.
Then, in response to pressing LOCAL/FUNCTION, the
unit will display “LLO” on its front panel display,
meaning Local lockout. In that case, only the GPIB
controller will be able to program the high voltage
output.
In Local mode, seven sequential pressings of the
LOCAL/FUNCTION pushbutton display the following
seven items:
x
GPIB address that the user has selected for the
unit.
x
Model number and output polarity setting (see
DISPLAY EXAMPLE 2.1)
x
Overvoltage trip response setting:
OE 0, OE 1
or OE 2
x
Overcurrent trip response setting:
OC 0 or OC
1
x
Overvoltage service request response setting: SrE
0 or SrE 1
x
Overcurrent service request response setting: SrC
0 or SrC 1
x
Software revision number
For a new OE, OC, SrE or SrC choice, press the
LOCAL/FUNCTION pushbutton to obtain the old choice
display. Then rotate the DIGITAL POTENTIOMETER
for the new choice. Descriptions of the available choices
follow below.
An eight pressing returns the display to voltage or current
readings as before the first LOCAL/FUNCTION
pushbutton depression.
4.3.1
CHOICE OF OVERVOLTAGE TRIP
RESPONSE (“OE”)
When a unit detects that output voltage is above its
programmed limit, it can respond by shutting itself off
(tripping) the high voltage. The syntax is:
OE2
Establishes that the unit cannot be programmed
to a voltage value above the voltage limit setting.
OE1
Enables the unit to shut down its output upon
detection of an output voltage above the limit setting.
OE0
Establishes that the unit will not shut down its
output in response to the detection of an output voltage
above the voltage limit setting
4.3.2 CHOICE OF OVERCURRENT TRIP
RESPONSE (“OC”)
When a unit detects that output current is above its
programmed limit, it can respond by shutting itself off
(tripping) the high voltage. The syntax is:
OC1
Enables the unit to shut down its output upon
detection of an output current above the limit setting
OC0
Establishes that the unit will not shut down its
output in response to the detection of an output current
above the voltage limit setting.
4.3.3 CHOICE OF OVERVOLTAGE SERVICE
REQUEST RESPONSE (“SrE”)
At the user’s choice, the unit can be made to issue a
service request to the GPIB controller in response to a
voltage overload. The syntax is:
SrE1
Enables SRQ in response to an
overvoltage detection.
SrE0
Disables SRQ in response to an
overvoltage detection.
4.3.4 CHOICE OF OVERCURRENT SERVICE
REQUEST RESPONSE (“SrC”)
