Section 3: Functions and features
Model 2651A High Power System SourceMeter® Instrument Reference Manual
3-88
2651A-901-01 Rev. A / March 2011
Digital I/O programming example
The programming commands below illustrate how to set Bit B1 of the digital I/O port high, and then
read the entire port value.
digio.trigger[1].mode = digio.TRIG_BYPASS
-- Set Bit B1 high.
digio.writebit(1,1)
-- Read digital I/O port.
data = digio.readport()
Using output enable
Overview
The Model 2651A digital I/O port provides an output enable line for use with a test fixture switch.
When properly used, the output of the System SourceMeter
®
instrument will turn OFF when the lid of
the test fixture is opened. See
(on page 2-42) for important safety information
when using a test fixture.
WARNING
When an interlock is required for safety, a separate circuit should be provided that meets the
requirements of the application to reliably protect the operator from exposed voltages. The
digital I/O port of the Model 2651A is not suitable for control of safety circuits and should not
be used to control a safety interlock.
Operation
When enabled, the output of the Model 2651A can only be turned on when the output enable line is
pulled high through a switch to +5 V (as shown). If the lid of the test fixture opens, the switch opens,
and the output enable line goes low, turning the output of the System SourceMeter
®
instrument off.
The output will not automatically turn on when output enable is set high. The output cannot be turned
back on until +5 V is applied to the output enable line.
Figure 69: Using the output enable line
