6 - Menu
18
QPX750 Instruction Manual
6.1.3
Logic Control
Menu>Instrument>Logic Control
Digital signal connections LOGIC IN and LOGIC OUT
are available from the terminal block on the ‘Rear
Logic Out
LOGIC OUT is an isolated rear-panel, open-collector output that will sink up to 2mA when active
(‘switch closure’); the LOGIC OUT can be set to be ‘closed on’ or ‘closed off’ for instrument operating
states: current limit (
CC
mode), power limit (
CP
mode), or for any fault trip. The default condition is for
LOGIC OUT to be ‘closed’ for the output on. Loss of AC power, which would deactivate the opto, is also
reliably detected with this setting.
Logic Out
has the following states: -
·
O/P On –
Main output is turned on.
·
Trip
- Any fault trip condition
OVP, OCP
etc.
·
CP
- PSU operates in Constant Power regulation mode.
·
CC
- PSU operates in Constant Current regulation mode.
Logic In
LOGIC IN is connected to the input of an isolating opto-coupler via an 820
Ω
resistor in series. The input
is activated by an input voltage greater than approximately 3.3V between LOGIC IN and LOGIC
COMMON.
Logic In
has the following states: -
·
Ignored
: Will not affect output.
·
Enable O/P
: Instrument will enable the output.
·
Disable O/P
: Instrument will disable the output.
NOTE
•
LOGIC IN can only be used to enable/disable the output if the output has already been turned
on with the front panel key or by remote interface command; this permits the front panel key
to be used to turn the output off in an emergency, i.e., to override LOGIC IN. Having turned
the output on with the key, the ON/OFF key remains illuminated even when the output is
disabled by the LOGIC IN signal.