Lightwave Communications manual Using the LDX-3232 Current Source’s Trigger Function

FUNCTIONS AND FEATURES

Using the LDX-3232 Current Source’s Trigger Function

C H A P T E R 5

Using the LDX-3232 Current Source’s Trigger Function

For applications where you need to synchronously initiate a measurement task from a remote instrument with the LDX-3232 Current Source, the Current Source offers a trigger output signal. The TTL pulse is initiated with any remote change in setpoint of the laser current source. A typical application for utilization of this feature is laser characterization tasks where an L-I curve is generated. For a programmed step in laser current, a light measurement can be triggered for each step in laser current. The trigger output is enabled only in remote mode via the GPIB/IEEE 488 GPIB Interface.

The trigger output is available via a standard BNC connector on the rear panel of the LDX-3232 Current Source. See Figure 5.1. The TTL pulse is approximately 13 µs wide and has a delay time of about 10-12 ms after the current setpoint is changed via GPIB. This delay does not include the GPIB transmission time. The time for any command to be sent via GPIB depends on the interface hardware and software control. The current setpoint may be changed by the LAS:LDI, LAS:INC, or LAS:DEC commands.

Note: The minimum step change time required for a corresponding trigger pulse is 20 ms. Care should be used with respect to the timing of any setpoint commands in relation to the actual hardware function. The INC and DEC commands have a minimum step time of about 20 ms that allows for the hardware initiation of a setpoint change and the settling of the output. The LAS:LDI command does not have any fixed delay for settling. With this command, some trigger pulses may be missed if the program step time is less than the 20 ms minimum.

A one shot trigger pulse will occur on power up of the instrument due to the states of the processor I/O.

Figure 5.1 LDX-3232 Rear Panel

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