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System Operation
4.6.3
TTL Output
The TTL Output signal is a TTL-Level output referenced to the unit's Digital
Ground. This signal is driven by an open-collector transistor output internally
pulled to +5V via a 1 k Ohm resistor. This is a general purpose output which
can be set via software (see TEC:TTL:OUT command) and used for
internal/external event synchronization. For convenience, digital ground is
located at pin 16 of the same connector.
4.6.4
LDD Current Monitor Output / Current Monitor Output
(Return)
The LDD Current Monitor Output and LDD Current Monitor Output (Return)
signals are a differential analog output loosely coupled to the unit's Laser
Diode Analog Ground. These signals allow the user to monitor the Model
6100 Laser Diode Driver subsystem's output current using an oscilloscope or
similar instrument. The output range is 0 to 10 V, which corresponds to the
output current range of 0 to Maximum Current.
4.6.5
LDD Voltage Monitor Output / Voltage Monitor Output
(Return)
The LDD Voltage Monitor Output and LDD Voltage Monitor Output (Return)
signals are a differential analog output loosely coupled to the unit's Laser
Diode Analog Ground. These signals allow the user to monitor the voltage
across the user's laser diode using an oscilloscope or similar instrument. The
default is to report the voltage at the Model 6100 Laser Diode Driver
subsystem's output connector. Alternatively, the voltage across the LD
Cathode Sense / LD Anode Sense signals will be reported if this has been
previously selected by a command received via USB interface. The output
range is 0 to the Maximum Compliance Voltage.
4.6.6
LD Cathode Sense / LD Anode Sense
The LD Cathode Sense and LD Anode Sense signals are a differential analog
input loosely coupled to the unit's Laser Diode Analog Ground.
Normally, the unit will measure and monitor the voltage drop at the rear panel
output connector using connections within the instrument, but this
measurement will not reflect the actual voltage drop across the user's laser
diode due to the voltage drop in the wiring between the unit and the user's
laser diode.
The LD Cathode Sense and LD Anode Sense signals are provided so that the
unit can measure and monitor the voltage drop across the laser diode. To
select these signals for voltage sensing, rather than the Model 6100 Laser
Diode subsystem connector pins, the unit must be commanded by an external
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