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Model 2790 SourceMeter

Switch System User’s Manual 2-5

Source readback – channels 13 and 25

The actual output of the selected source can be veriﬁed by using source readback, which

routes the selected source back to the DMM of the 2790 for measurement. I-source and

V-source readback are explained in Section 5.

• Opening channel 22 and closing channels 21, 25, and 18 connects the I-source

sense resistor to the DMM of the Model 2790.

• Closing channels 22, 21, 13, and 18 connects the V-source to the DMM of the

Model 2790.

Interlock – J106

A 7751/7752/7753 module has an interlock to disconnect its I-source and V-source from

the rest of the switch matrix. In order to use the module sources, interlock must be

enabled. The interlock switch of a test station is connected to the J106 terminals of the

module. When the interlock switch is open (i.e., safety shield open), the sources cannot be

connected to the switch matrix. Details on interlock are provided in Section 5.

NOTE The Interlock switch does not affect the output of J107. Voltage can still be present

at those terminals even if the interlock is disabled. See “General purpose terminal

blocks – J105, J107, and J108” for additional details.

General purpose terminal blocks – J105, J107, and J108

There are quick-disconnect terminal blocks available to the user to provide access to various

switching module components. These are provided for general purpose test applications that

are not necessarily related to airbags.

J105 (matrix backplane and guard)

The backplane terminals provide access to the relay matrix backplane. The matrix backplane

is the primary “artery” for signal routing though the module.

The guard terminals are typically used for shielding when using the V-source and I/V con-

verter for high ohms measurements. Guard connections are explained in Section 4.

J107 (source outputs and guard)

The I-source and V-source (7751/7753) are always on and can be accessed by the user at

J107. The programmed output is routed to these terminals.

The guard terminals are typically used for shielding when using the V-source and I/V

converter for high ohms measurements. Guard connections are explained in Section 4.

Keithley 2790 User Manual

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