Model 2461 Interactive SourceMeter® Instrument Reference Manual
Section 2: General operation
2461-901-01 A/November 2015
2-121
TSP command programming example
-- Reset the instrument to default settings.
reset()
-- Enable the contact check function.
smu.contact.enable = smu.ON
-- Set the contact check threshold level to 15 ohms.
smu.contact.threshold = smu.THRESHOLD_15_OHM
-- Enable 4-wire remote sense.
smu.measure.sense = smu.SENSE_4WIRE
-- Check connections for contact resistance exceeding 15 ohms. Get the result of
the contact check test to see if any connections failed.
print(smu.contact.check())
-- Check the high, low, and guard connections for excessive contact resistance. Get
the result of the contact check test to see which, if any, connections failed.
print(smu.contact.checkall())
-- Disable the contact check function.
smu.contact.enable = smu.OFF
Protection
The Model 2461 provides several methods for ensuring that the source remains within certain values.
This helps to protect the device under test (DUT) from damage.
The protections that affect the source are the:
•
Overvoltage protection.
This is the voltage at the instrument terminals.
•
Source limits.
This is the sourced value at the device.
Overvoltage protection
Overvoltage protection restricts the maximum voltage level that the instrument can source. It is in
effect when either current or voltage is sourced. This protects the device under test (DUT) from high
voltage levels.
For example, if a sense lead is disconnected or broken during a 4-wire sense measurement, the
instrument can interpret the missing sense lead as a decrease in voltage and respond by increasing
the source output. If overvoltage protection is set, the sourced output is not allowed to exceed the
overvoltage protection limit.
The value set for overvoltage protection takes precedence over the source limit settings. When it is
enabled, it is always in effect.
When overvoltage protection is set and the sourced voltage exceeds the setting:
•
The output is clamped at the overvoltage protection value
•
On the front panel, an indicator to the right of the voltage displays OVP
When overvoltage protection is used in a test sequence, it should be set before turning the source on.
Even with the overvoltage protection set to the lowest value (2 V), never touch anything
connected to the terminals of the Model 2461 when the output is on. Always assume that a
hazardous voltage (greater than 30 V
RMS
) is present when the output is on. To prevent
damage to the device under test or external circuitry, do not set the voltage source to levels
that exceed the value that is set for overvoltage protection.
