Thermalyze Operation

Instrument Control

The topics in this section explain how to setup and control Keithley power supplies and source measure units during lock-in thermography, thermal model comparison, and sequence tests.

Overview Instrument Control Settings Startup Settings Safety Settings IV Curve

Overview

Instruments are DC power supplies and source measure units that can be controlled by Thermalyze via USB or GPIB interface to output voltage and current to an electronic device during Sequence, Thermal Model Comparison (TMC), and Lock-in Thermography (LIT) tests.

Manufacture Info: Refer to the instrument manufacturer documentation for detailed specifications and instructions regarding appropriate instrument settings and making proper electrical connections.

Supported Keithley Instruments

2280S DC power supplies
2400, 2401, 2410, 2420, 2440 standard source measure units
2450, 2460, 2461, and 2470 graphical source measure units
2601A, 2601B, 2602A, 2602B, 2604B, 2611A, 2611B, 2612A, 2612B, 2614B, 2634B, 2635A, 2635B, 2636A, 2636B, 2657A source measure units

Computer Control Interface

Some instrument models include a USB port for direct connection to a computer USB port. Other instrument series only include a GPIB (IEEE-488) port that will require a National Instruments USB GPIB controller model GPIB-USB-HS+ to connect to the computer USB port.

Cycle Power: When switching between USB and GPIB instrument interface, the instrument power may need to be cycled.

Shared Settings: Instrument settings are shared between Sequence, TMC, and LIT tests. For example, if changes to settings are made to Instrument settings when setting up or opening a lock-in test, the changed settings will apply if a Sequence test is subsequently performed. In this case, Program Settings can be used to restore settings to a previous state prior to performing the Sequence test.

Thermalyze Test Instrument Control

Sequence Tests

When the Record Images button is pressed on the Sequence toolbar, the Instrument source voltage is set to the Voltage High setting and the output is turned on. Instrument measurements are conducted immediately after each voltage output change and displayed on the instrument front display.

Thermal Model Comparison Tests

When a TMC test is started, the Instrument source voltage is set to the Voltage High setting and the output is turned on. When the test ends, the output is turned off and the source voltage is set to 0 volts.

Lock-in Thermography Tests

When a lock-in test is started, the Instrument source voltage is set to the Voltage High setting and the output is turned on. Instrument voltage and output are controlled during each LIT test cycle according to Power Mode settings and the status of setting Turn Output Off at 0V.

Instrument Measurements During Tests

Instrument measurements are conducted immediately after each output change and displayed on the instrument front display.

Important: When a test ends, the instrument output is turned off and voltage (when sourcing voltage) or current (when sourcing current) is set to zero.

Instrument Model Feature Support

Instrument Feature	2280S	2400, 2401, 2410, 2420, 2440	2450, 2460, 2461, 2470	2601A, 2602A	2601B, 2602B, 2604B	2611A, 2612A, 2635A, 2636A, 2657A	2611B, 2612B, 2614B, 2634B, 2635B, 2636B
Computer Control Interface	USB/GPIB	GPIB	USB/GPIB	USB/GPIB	USB/GPIB	USB/GPIB	USB/GPIB
Command Protocol	SCPI	SCPI	SCPI, TSP	TSP	TSP	TSP	TSP
Sourcing Voltage/ Current	voltage only
Channel A/B	channel A	channel A	channel A	channel A/B	channel A/B	channel A/B	channel A/B
Source Range		*
Terminals	front	front and rear	front and rear	rear	rear	rear	rear
Sounds
Breakdown Protection
Output Off Mode	normal only
High Capacitance Mode
Display Digits
NPL Cycles
Auto Zero
Reset Defaults
Turn Output Off at 0V
Test Start Check		output enable†	interlock	output enable*	output enable*	interlock	interlock
Remote Mode Continuous Measurement Triggering††

* For the 2400 series, Voltage and Current Range entries are ignored and output ranges are determined by Voltage and Current Limits.

† According to Tektronix (Keithley) product documentation, the output enable feature is not suitable for control of safety circuits and should not be used to control a safety interlock. 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.

†† When controlling an instrument remotely via USB or IEEE-488, continuous measurement triggering enables the instrument to conduct measurements continuously when the Test box is checked in the Instrument Control window. If this feature is not available on your instrument, then the Timed: Enable box must be checked to conduct measurements while testing the instrument output.

Troubleshooting

Communication Error "TSP Syntax error"

When attempting to communicate in SCPI Protocol with the Keithley graphical source measure units' model 2450, 2460, 2461, or 2470 and "TSP Syntax error..." is displayed on the instrument, the instrument's Command Set needs to be changed to SCPI.

On the instrument push the Menu button and then on the touch screen select System >> Settings >> Command Set >> SCPI.
Reboot the instrument when prompted.

Communication Error "SCPI Syntax error"

When attempting to communicate in TSP Protocol with the Keithley graphical source measure units' model 2450, 2460, 2461, or 2470 and "SCPI Syntax error..." is displayed on the instrument, the instrument's Command Set needs to be changed to TSP.

On the instrument push the Menu button and then on the touch screen select System >> Settings >> Command Set >> TSP.
Reboot the instrument when prompted.

Lost USB Communication

If communication is lost between the instrument and computer and cannot be reestablished, the cause may be due to USB buffer corruption.

First try clicking the Open Connection button to clear the computer USB buffers.
If this does not resolve the issue, cycle instrument power to clear the instrument USB buffers.

Incorrect Measurement Readings

Instrument voltage and current are read and displayed at specific times during a test. Instrument settings including Voltage High and Low, High Capacitance Mode, Current Limit, NPL Cycles, and Auto Zero determine the instrument output response time. After checking a Test checkbox to turn on the low or high voltage output when setting up a test, the Take Reading button may need to be clicked several times to read and display the settled output voltage and current. During a test, increase the Reading Delay setting to delay measurements, allowing adequate time for the instrument output to settle and to conduct measurements. The timing of readings on the instrument panel depends on

Irregular Instrument Readings

When operating in Pulse Power Mode and Pulse Length is short (<100 ms), the timing of readings displayed on the instrument panel may be irregular due to overlap of measurements and fast output changes.

Instrument Buffer Overflow

During a lock-in test, commands are sent to the instrument through the USB interface. If the instrument is unable to process all commands before receiving additional commands, the additional commands will accumulate in the instrument buffer, resulting in corruption of output timing. Enabling High Capacitance Mode will slow instrument output response and may result in instrument buffer overflow at test cycle frequencies above 1Hz. If a test has been started at a high Cycle Frequency and buffer overflow has occurred, instrument power may need to be cycled to clear the buffer.

Windows USB Power Saving

If intermittent disruptions in communication occur or when running tests for long periods of time (hours or overnight testing), disable the Windows USB power saving feature.

Open Windows Device Manager.
Locate the instrument in the list and then right-click and select Properties.
On the General tab note the Hub #.
Expand Universal Serial Bus controllers.
Right-click each USB Hub and on the General tab, identify the hub on which the device is located.
When the correct hub is identified, select the Power Management tab and uncheck "Allow the computer to turn off this device to save power".
Clock OK to close Device Manager.

Instrument Control

Description

To open the Instrument Control window (see Figure 1), click the button on the Sequence toolbar, of select the Instrument Control item from the Setup menu (or click the button on the top toolbar) of the Thermal Model Comparison window or Lock-in Thermography window.

Figure 1: Instrument Control window

Setup Menu

Settings	Open the Instrument Settings window.
Startup	Open the Instrument Startup window.
Safety	Open the Instrument Safety window.

Instrument Selection

Detect Instruments	Click this button to detect the instruments connected to the computer and list them in the Select Connected Instrument combo box. The instruments that can be detected are Keithley USBTMC (USB test and measurement class) via USB instrument interface and USBTMC via GPIB instrument interface.
Select Connected Instrument	Select a connected instrument to use. Instruments with a USB interface are listed, for example, as "USB0::0x05E6::0x2612::4482980::INSTR" where "USB0" designates the USB interface, "0x05e6" designates the Keithley Instruments vendor ID, "4482980" designates the instrument serial number, and "0x2612 designates the model number, and "INSTR" designates the USBTMC protocol. Instruments with a GPIB interface are listed, for example, as "GPIB0::18::INSTR" where "GPIB0" designates the GPIB interface, "18" designates the GPIB address selected on the instrument, and "INSTR" designates the USBTMC protocol.
Open Connection	Click this button to establish a connection with the selected instrument. Note: A connection to the instrument must be opened before the instrument can be controlled.
Enable Instrument	Check this box enable the instrument for use during Sequence, TMC, and LIT tests. Note: When this box is checked, the instrument output is used in place of Sequence Relays, TMC Relays, and LIT Relays. Important: The Instrument Control window must be open to issue commands to the instrument during Sequence, TMC, and LIT tests.

Instrument Information

Select Model

Select the model that is selected in the Select Connected Instrument combo box.

Command Protocol

Select the instrument communication protocol, SCPI (Standard Commands for Programmable Instruments) or TSP (Test Script Processing). SCPI is an older generic command set supported by older instruments. TSP is a Keithley proprietary command set supported by newer Keithley instruments. Not all Keithley instruments support both protocols.

Important: The protocol will also need to be selected on the instrument. On a 2450 graphical series source measure unit, the communication protocol can be found under System >> Settings >> Command Set.

Source Settings

Sourcing	Choose to source either voltage or current.
Channel	Choose the instrument channel to use.
Setup Instrument	Click this button to setup the instrument with the selected source and measure settings. When instrument settings are changed, the message "* Setup Required" is displayed to the right of the button until the instrument has been setup with the new settings. Note: The instrument must be setup before a test can be started.

Source Voltage

Voltage High	Enter the output voltage during a Sequence or TMC test, and the first half of each cycle of a lock-in test. Note: The voltage measurement range is determined by the larger absolute value of the Voltage High and Low settings.
Voltage Low	Enter the output voltage during the second half of each cycle of a lock-in test.
Current Limit	Enter the maximum output current. Note: This value may be automatically limited to the Safety Current Limit if the source voltage exceeds the Safety Voltage Limit. Important: When Current Limit is exceeded during a test, instrument output response may slow significantly as output voltage is reduced to lower current below the limit level. This may result in voltage and current readings that do not reflect values when the output settles.
Current Range	Enter the current measurement range. When testing circuits with high capacitance or inductance, setting the range higher than Current Limit can help prevent damage to instrument output circuitry. To set the current measurement range equal to Current Limit, set this value lower than Current Limit. Note: Some instrument models require Current Limit to be within a specific percentage of Current Range and will issue an error if this value is set too high.
Test	Check a box to turn on and test the instrument high or low voltage output. Uncheck a box to turn off the output. These boxes are used during test setup to confirm electrical connection and to evaluate power and resistance dissipation in a defect to estimate required testing time.

Source Current

Current	Enter the output current during a Sequence or TMC test, and the first half of each cycle of a lock-in test. Note: The current measurement range is determined by this setting.
Voltage Limit	Enter the maximum voltage output. Note: This value may be automatically limited to the Safety Voltage Limit if the source voltage exceeds the Safety Current Limit. Important: When Voltage Limit is exceeded during a test, instrument output response may slow significantly as output current is reduced to lower voltage below the limit level. This may result in voltage and current readings that do not reflect values when the output settles.
Voltage Range	Enter the voltage measurement range. When testing circuits with high capacitance or inductance, setting the range higher than Voltage Limit can help prevent damage to instrument output circuitry. To set the voltage measurement range equal to Voltage Limit, set this value lower than Voltage Limit. Note: Some instrument models require Voltage Limit to be within a specific percentage of Voltage Range and will issue an error if this value is set too high.
Test	Check a box to turn on and test the instrument current output. Uncheck a box to turn off the output. This boxes is used during test setup to confirm electrical connection and to evaluate power and resistance dissipation in a defect to estimate required testing time.

Measurement Readings

Timed: Enable	Check the Enable box to conduct real-time instrument measurements on the instrument front panel which are then displayed at the bottom of the Instrument Control window. Timed readings are performed when a voltage or current test box is checked and during Sequence and TMC tests. Important: When controlling an instrument remotely via USB or IEEE-488, continuous measurement triggering enables the instrument to conduct measurements continuously when the Test box is checked (see above). If this feature is not available on your instrument, then the Timed: Enable box must be checked to conduct measurements while testing the instrument output. See the Instrument Model Feature Support table to determine if your instrument support continuous measurement triggering.
Reading Rate	Enter the real-time instrument read frequency.
Lock-in Test: Enable	Conduct real-time instrument measurements on the instrument front panel which are then displayed at the bottom of the Instrument Control window. LIT Test readings are performed during LIT tests after changes in output. Note: Measurements can be read from the instrument during LIT tests only when Cycle Frequency is 1Hz and lower to prevent disrupting cycle test timing.
Read Delay	This setting determines when current and voltage are read from the instrument after a change in output during a lock-in test. Increase this setting to delay current and voltage measurements, allowing adequate time for the instrument output to settle and to conduct measurements. Note: Changes in output voltage and current and their measurement are very fast but not instantaneous. Additionally, the magnitude of voltage and current output and settings including High and Low, High Capacitance Mode, Current Limit, NPL Cycles, and Auto Zero determine instrument output settling time and measurement speed.
Take Reading	After checking a voltage or current test box to turn on instrument output, click this button to read and display the output current and voltage until the instrument output has settled.
Send Values	Click this button to send the values in the Current, Voltage, Power, and Resistance fields to the status bar in the Lock-in Thermography window and to the Lock-in Advanced Save and Export window.
IV Curve	Click this button to open the IV Curve window.
Current [mA]	Display field for the measured current in units of milliamps.
Voltage [V]	Display field for the measured voltage in units of volts.
Power [µW]	Display field for the power dissipation in the resistive short circuit of leakage current site in units of microwatts. Power is calculated by multiplying the measured current and voltage. Tip: Power dissipation in a resistive short is used to estimate the LIT test time required to detect the defect.
Resistance [Ω]	Display field for the resistance of the short circuit of leakage current site in units of ohms. Resistance is calculated by dividing the measured voltage by the measured current.

Settings

The Instrument Settings window (see Figure 2) is used to set instrument parameters. To open this window, click the Instrument Settings item under the Setup menu (or click the button on the top toolbar) of the Instrument Control window.

Figure 2: Instrument Settings window

System Settings

Terminals	Select the front of rear terminals on the instrument for output.
Sounds	Enable or disable instrument sounds.
Breakdown Protection	Due to the limited bandwidth of the Keithley 2470 source meter, current output may exceed the programmed or current limit value. Over current conditions are more likely to occur at high voltage transitions and when test circuit capacitance is high. To limit output current, breakdown protection adds a 500 Ω resistor in series with the source output. When set to Auto, the resistor is automatically added when the voltage range is 200 volts or higher and when the current range is less than or equal to the 10 mA. When the voltage range is below 200 volts or the current range is above 10 mA, the breakdown protection resistor is automatically removed.

Source Settings

Output Off Mode

Select the state of the output terminals when the source of the instrument is turned off. This setting places the instrument in a known, non-interactive state during idle periods, such as when you are changing the device under test.

Important: When the High Impedance state is selected and the output is turned off, the output relay opens, disconnecting the instrument as a load and disconnecting external circuitry from the inputs and outputs of the instrument. To prevent excessive wear on the output relay, do not use High Impedance state for tests that turn the output off and on frequently.

High Capacitance Mode

When the instrument is measuring low current and is driving a capacitive load, you may see overshoot, ringing, and instability. You can enable the High Capacitance Mode to minimize these problems.

Important: Enabling high capacitance mode will slow instrument output response and may result in instrument buffer overflow when LIT test Cycle Frequency is higher than 1Hz.

Note: This setting applies only when operating in 1 μA and above current ranges.

Measure Settings

Display Digits	Enter the number of digits that are displayed for measurements on the instrument front panel.
NPL Cycles	Enter The amount of time that current and voltage are measured. The amount of time is specified as the number of power line cycles (NPLCs). Each PLC for 60 Hz is 16.67 ms (1/60) and each PLC for 50 Hz is 20 ms (1/50). The shortest amount of time results in the fastest reading rate but increases the reading noise and decreases the number of usable digits. Note: If you change this setting, you may want to adjust the Display Digits settings to reflect the change in usable digits.
Auto Zero	Check this box to set the instrument so that it periodically gets new measurements of its internal ground and voltage reference. This setting increases measurement accuracy, but may slow measurement time.

Test Settings

Reset Defaults	Check this box to reset the instruments default settings when the Setup Instrument button is clicked.
Turn Output Off at 0V	When this box is checked, sourcing voltage and low voltage is set to 0 volts, instrument output is turned off during the second half of each cycle of a lock-in test. When this box is unchecked and Voltage Low is set to 0 volts, instrument output remains on during the second half of each cycle even when Voltage Low is set to 0 volts.

Interlock

Test Start Check

Check this box to retrieve the status of the instrument interlock prior to starting a Sequence, Thermal Model Comparison (TMC), or Lock-in Thermography (LIT) test.

Startup Settings

The Instrument Startup window (see Figure 3) is used to set source settings on the Instrument Control window upon program startup. To open this window, click the Instrument Startup item under the Setup menu (or click the button on the top toolbar) of the Instrument Control window.

If the box is checked next to a setting, that setting is loaded into the Instrument Control window at program startup.

Figure 3: Instrument Startup window

Safety Settings

The Instrument Safety window (see Figure 4) is used to set safety current and voltage limits that apply to the source and limit settings on the Instrument Control window. To open this window, click the Instrument Safety item under the Setup menu (or click the button on the top toolbar) of the Instrument Control window.

Figure 4: Instrument Safety window

Enable	Check this box to enable safety current and voltage limits.
Safety Current Limit	When voltage is sourced and exceeds the safety voltage limit, the current limit will be automatically limited to this value. Maximum value is 5mA.
Safety Voltage Limit	When current is sourced and exceeds the safety current limit, the voltage limit will be automatically limited to this value. Maximum value is 30 V.

Current Danger Levels

Figure 5: Current danger levels

IV Curve

A device's current response to an applied voltage can be plotted using an Instrument. Use the settings in the Instrument Control window and Instrument Settings window to set instrument parameters prior to plotting an IV curve.

To open the IV Curve window (see Figure 6), click the IV Curve button in the Instrument Control window.

Voltage Sourcing: Sourcing must be set to Voltage in order to plot an IV curve.

Figure 6: IV Curve window

File Menu

Open Curve	Select the binary IV curve file (.oivc) to open.
Save Curve	IV curves are saved in binary format with a ".oivc" extension. Note: When saving an iv curve file, the file name that you provide is appended with ".oivc" and saved in the "Optotherm\Thermalyze\IV Curves" folder unless you specify a different folder. Note: The file name of the most recently opened or saved file is displayed at the bottom of the window.
Export Window	The IV Curve window can be saved to file in the following formats: bmp, jpg, png, and tif. The size of the exported image is proportional to the size of the window. Note: Exported IV Curve windows are saved in the "Optotherm\Thermalyze\Export" folder unless you specify a different folder.
Export Data	The iv curve data values can be saved to file in ASCII text format (.txt) or binary format (.imb) for import into a spreadsheet program or your own custom application. In ASCII text format, each x-axis voltage is saved followed by the y-axis current in milliamps. A tab character separates voltage and current values. A newline character (carriage return/line feed) separates each voltage and current pair. In binary format, all data is saved sequentially with no separators. Both x-axis voltage and current are saved as four-byte floating-point values in little endian format.
Print	Print the IV Curve window. Note: You must have a printer connected to your computer.
Print with Preview	Select this menu item to open the Print Preview dialog before printing.

Plot Controls

Data Points	This field displays the number of voltage-current data points in the plot. Note: The total number of points in the plot is equal to the number of Voltage Steps plus one.
Clear All Data	Click this button to clear all data from the plot.
Select	Select this button when finished zooming or panning to allow placement of the vertical cursor on the plot.
Zoom In	Select this button to zoom into the plot. Click and drag on the plot select a rectangular area to zoom into.
Zoom Out	Click this button to zoom out of the chart one level. Continue clicking this button to zoom out additional levels.
Zoom Out Completely	Click this button to set the x-axis and y-axis ranges to the bounds of the plot data.
Pan	Select this button and then drag on the plot to pan.
Auto Range New Data	Press this button to automatically reset the x-axis and y-axis ranges to the bounds of the plot data each time new data is plotted.

Setup

Voltage Steps	Enter the number of voltage steps to plot between the Voltage High and Low settings on the Instrument Control window. The step size is displayed on the right and is calculated by subtracting Voltage Low from High and then dividing the result by the number of steps.
Step Delay	Enter a time delay between voltage steps when plotting.

Plotting

Start	Start applying voltage steps and plot corresponding current draw.
Stop	Stop applying voltage and stop plotting. Important: The instrument output is turned off and voltage is set to zero when an IV curve plot is complete or has been stopped.

Cursor Data

Click on the plot to position the vertical cursor and select a data point to display the corresponding applied voltage and current response.

Top of page