Local Operation
Series 2268 850 Watt DC Power Supplies Reference Manual
54
2268S-901-01 Rev. A / January 2015
Defining the Polarity of the External Shutdown Signal
1.
Turn the 9-position mode control to the PRT position or press the rotary
Adjust/Enter control if the control knob is already at the PRT position.
is displayed on the output voltage display.
2.
Turn the rotary Adjust/Enter control until
is displayed.
3.
Press the rotary Adjust/Enter control to display
(shutdown on logic 0) or
(shutdown on logic 1).
4.
Press the rotary Adjust/Enter control to commit the desired polarity setting.
For example: If you set the shutdown logic to 1 (
) and apply a logic high (greater
than 1.2 Vdc) to pin J3.12 relative to pin J3.6 on the ISOL connector, the power supply
will shut down. Conversely, if you set the shutdown logic to 0 (
), the power supply
will only operate when you have a logic high (greater than 1.2 Vdc) to pin J3.2 relative
to pin J3.6.
Important:
There is an internal pullup resistor inside the shutdown circuit so
the shutdown polarity should be set to 0 if it is not being used.
The SCPI command (s) for these instructions are:
[:]OUTPut[<channel>]:POLarity
LOOP PROTECTION
The Loop Protection feature can be used to enable or disable multiple units in daisy chain
configuration through the AUX Output and Isolated Analog Programming Connector, J3. Up
to four units (example, Units #1 through #4) can be configured in Loop Protection; if one of
the units is experiencing a fault condition, other units in the same loop will disable their
output simultaneously. This is achieved by connecting Unit #1’s MAIN_PS_GOOD to Unit
#2’s SD (Shutdown Main O/P) and continues until Unit #4’s MAIN_PS_GOOD is fed to
Unit #1’s SD (Shutdown Main O/P). Common applications include single master controlling
multiple slave units as a system On/Off. In addition, any fault from either operating unit will
cause the system to disable.
The Loop Protection can be enabled or disabled locally using the front panel 9-position mode
control, or remotely using a SCPI command.
Important:
While Loop Protection is enabled (ON), the external shutdown
function will be automatically set to low active. When Loop Protection is
disabled (OFF), the external shutdown function will be set to the user’s last
setting.
Setting up Loop Protection
To set up Loop Protection:
With the AC powered OFF, connect the first unit’s pin J13.13 to the next unit’s J 13.12 on the
AUX Output and Isolated Analog Programming Connector. Do this for up to four units. An
example of a 3-unit loop protection is illustrated as follows:
Summary of Contents for Keithley 2268 Series
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