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slice:qt

SLICE-QT Four-Channel Temperature Controller

Model No. SLICE-QT

Document Revision: 1

Document Last Updated on 2019/01/21 17:42

Please read Limited Warranty and General Warnings and Cautions prior to operating the SLICE-QT.

SLICE-QT Quick Start Guide
SLICE-QT web page
Please check back for added functionality. Contact sales [at] vescent [dot] com for questions and corrections, or to request added functionality.

Description

The SLICE-QT is a high-precision temperature controller (see figure 1). It will control up to four thermal plants with sub-millikelvin precision.

Fig. 1: The SLICE-QT

Purchase Includes

  • SLICE-QT Temperature Control Unit
  • AC power cord with appropriate wall plug for you location (if known)
  • Four single-ended 6-ft control cables1)

Absolute Maximum Ratings and Power Input

Note: All modules designed to be operated in a laboratory environment.

Parameter Rating
Environmental Temperature >15°C and <30°C
Environmental Humidity <60%
Environmental Dew Points <15°C
Maximum AC Line Input Current 2 A
Tab. 1: Absolute Maximum Ratings

The SLICE-QT will accept input line voltages within the ranges shown in table 2.

Parameter Value Units
Input Line Voltage 100-240 VAC
Frequency 50-60 Hz
Phase 1 phase
User-serviceable fuse2) T 2.0 A L 250V
Tab. 2: Input Voltage Specifications

Proper Usage

Any input/output connections to the SLICE instrument must be derived from a Safety Extra Low Voltage (SELV) source.
If this instrument is used in a manner not specified by the manufacturer in this manual or other relevant literature, protection provided by the instrument may be impaired.

List of Symbols

Warning. Pay special attention to procedures and notes. If procedure is not followed carefully, damage to the SLICE-QT or devices connected to it may occur.
Potential for electrical shock hazard.

Specifications

Performance3)
Parameter Value
Channels 4
Loop FIlter PID, adjustable corners and proportional Gain
Control Range4) -10 to +120°C
Compatible Transducer TEC or resistive heater
Compatible Sensor NTC thermistor 5)
Temperature Stability ±0.2 mK over 1 hour6)
Precision ~1 mK
Control Capacity 35 W7)
Current Capacity 6 A per channel8)
Compliance Voltage ≤18 V9)
Input & Output
I/O Voltage Range ±10 V
Triggering TTL
Control Interface
Control Front-panel touch screen, GUI, Serial API
Connections Host control: USB Type B
Tab. 3: Specifications of SLICE-QT

Front Panel

An image of the front panel is shown in figure 2. The functions and connections are as follows:

  1. Parameter input adjustment knobs
  2. Control signal inputs
  3. Signal monitor outputs
  4. Touch screen with view of CH 2 Details screen
  5. ∆T plotted as a function of time (blue line)
  6. System locked range (yellow dashed lines)

Fig. 2: Front of SLICE-QT

Rear Panel

An image of the rear panel is shown in figure 3. The functions and connections are as follows:

  1. Main On/Off power switch
  2. AC line power in10)
    1. User-serviceable fuse (T 2.0 A L 250V)
  3. Output trigger (BNC)
  4. Input trigger (BNC)
  5. USB port (Type B)
  6. Connections to thermal plants11)12)

Fig. 3: View of rear of SLICE-QT

Interface Connections

Connections to the thermal plants are made from the rear panel. Four cables for this purpose are provided with the SLICE-QT. Each has one end terminated with a CUI Inc. PDP-40 connector for connecting to the CUI Inc. CP-7240-ND connector on the SLICE-QT. The other end is unterminated and is for connecting to your specific plant. The pin out for connecting the cable (Beldon 1502R 010500) to your specific plant is given in table 4.

Connector
Pin Number
Color Function AWG
1 Red TEC/Heater+ 18
2 Black TEC/Heater- 18
3 White Thermistor+ 22
4 Blue Thermistor- 22
Metal Sleeve Ground Shield 24
Tab. 4: Cable pinout
Do not have servo loop engaged when connecting Servo Output to your plant.
It is suggested to not ground the cable shield at the transducer end of the interface cable as ground loops may be formed, degrading performance.

You may purchase more cables separately from Vescent Photonics. We do not recommend making cables, but if you do so, make sure the metal sleeve is well grounded to provide proper shielding to the signal cables.

General Concepts

Screen Navigation

The touch screen interface and the Host GUI operate in a substantially similar way, except touch is substituted for a click in the touch screen interface.

When presented with a given view, it is possible to select the functionality or edit the values in a field bordered in blue. When a particular field is actively being edited, its border will change to yellow. The Home Screen of the SLICE-QT is shown in figure 4. From the Home screen, summary control over the four channels is possible, including setting Tset, initiating lock, or entering an individual channel's Detail screen.

In general, the status displayed in an editable field is the current status (not the result of touching the button). Touch the field to select a new value/status. For instance, in figure 4 all of the channels are in stand by. Touching the OFF button to initiate servo control over a plant will change this button to read ON (figure 15). Fig. 4: Home screen of SLICE-QT

Control Bar

On the left edge of the screen is the Control Bar. At any given time, these buttons will have the following effect.

Home Button

Fig. 5: Home button Returns to Home screen (figure 4).

Back Button

Fig. 6: Back button Returns to previous screen. Changes will be lost if not accepted before using the Back button.

Lock Button

Fig. 7: Lock button (shown in unlocked mode) Locks out further modification of parameters. Touch to lock or unlock parameter entry. It is still possible to engage the temperature control loops when system is locked, but it is not possible to change the set point temperature or loop parameters, etc.

I/O Button

Fig. 8: I/O button Enters the screen for programming the front-panel I/O.

System Settings Button

Fig. 9: System settings button Enters screen for system control settings (brightness, volume, etc.).

Entering Values

In order to afford maximum resolution, the least significant digit will not necessarily change to precisely your target value and will be coerced to the nearest acceptable value, which is limited by the digitization scheme for the set point. For instance, you may select a set point temperature of 17.000°C, but the closest allowed digitized value may be 16.999°C.

In most instances, there are two methods for entering parameter values: the physical rotary knobs on the front panel and the pop-up keypad on the touch screen. When using the knobs to change the value of a parameter, changes take effect immediately. When using the keypad, changes do not take effect until the enter key is depressed.

Rotary Knobs

If you touch an editable field for a brief moment, a cursor will appear under one of the digits of the parameter value. By turning the right knob, it is possible to increase (cw) or decrease (ccw) the value of the underlined digit. Turning the left knob will change which digit is editable (cw to move to the left and ccw to move to the right).

Keypad

If you touch and hold an editable field such as the set point temperature, a numeric keypad will appear as seen in figure 10. You can enter in the full value of the desired parameter with this keypad.
Fig. 10: Pop-up Keypad

The action initiated by each button is described below.

Escape

Fig. 11: Escape button Exits keypad without accepting changes.

Clear

Fig. 12: Clear button Clears value in field being edited.

Delete

Fig. 13: Delete button Deletes last character entered.

Enter

Fig. 14: Enter button Accepts edits and exits keypad.

Home Screen

The Home screen summarizes the status of all four channels (figure 4). The data for each channel is arranged vertically. At a glance, for each channel, Tset, Tact, and ∆T can be read, as well as whether servo control is engaged. If the loop is engaged and ∆T is smaller than a user-defined range, the Error value field will be green, indicating a locked state. If ∆T is outside this user-defined range, this field will turn yellow.

Setting the Temperature

To set the temperature set point from the home screen, touch the Setpoint window for the desired channel (circled in red for CH 1 in figure 15). A long touch will cause a keypad to appear. Enter desired value and touch the accept button.

A short touch will highlight the Setpoint window in yellow (figure 16). Use rotary knobs to select digit to edit (right knob) and value for digit (left knob).
Fig. 15: Select Temperature setpoint for CH 1

Fig. 16: Knob adjustment of Temperature setpoint for CH 1

Enabling Feedback

Touch the OFF button at the bottom of the column for the desired channel. The button will turn white and read ON to indicate the SLICE-QT is actively controlling the temperature for that channel. In figure 15 and figure 16 CH 1 is active and CHs 2-4 are inactive.

When the system is locked (as defined by the user in the CH X > Settings > Limits screen) the Error window will display ∆T with a green background. As the system approaches lock, it will display ∆T on a yellow background.

Channel Detail Screen

You can set how individual channels behave in the Channel Detail screen. To enter a Channel Detail screen from the Home screen, touch the CH button for the appropriate channel (figure 4). figure 17 shows the CH 1 Detail screen. From this screen, you can change Tset, and initiate temperature control as from the Home screen. You can also visually monitor the performance of the loop. The graph in the lower right of the screen displays ∆T (Tact - Tset) on a rolling basis. The yellow dashed lines indicate the user-defined “lock range.” In figure 17, the lock range is set to ±3 mK. If ∆T is outside of this range, the Error field will change from green to yellow.

You can also set the various parameters for how the loop will behave. Fig. 17: Initial view of CH 1 Detail screen

Setting Control Modes

Touch the Settings button in the top right of the window. The sub-menu shown in figure 18 will appear. Fig. 18: Menu of settable parameters

Adjusting the Graph

To adjust the vertical range (∆T) of the graph from the Details screen, touch Settings > Y Scale. Select the appropriate setting (figure 19). Fig. 19: Setting the y-scale on ∆T vs. t graph

To adjust the time base of the graph from the Details screen, touch Settings > X Scale. Select the appropriate setting.

Channel Settings

PID Filter and Slew Rate Adjustment

Fig. 20: Screen for adjusting PID parameters for individual channel

To set the PID loop filter parameters from the Home screen, select CH X > Settings > PID Params and the screen in figure 20 will appear. The parameters for the PID loop filter are set in this popup screen. These parameters control the closed-loop behavior of the feedback. Each of these parameters will need to be tuned specifically for your plant. There is an option to enable or disable each parameter in the loop filter. There are a number of methods to tune a loop. We recommend the Ziegler-Nichols method.13)

For applications where the rate of change of the temperature of the plant needs to be controlled, it is possible to set an upper limit on the slew rate. This can also be done through the PID Params screen.

Setpoint ºC Sets the setpoint temperature of the plant.
Proportional V/V Sets the proportional gain of the loop filter.
Integral sec Sets the integral time constant of the loop filter.
Derivative sec Sets the derivative time constant of the loop filter.
Slew (Rate) ºC/min Sets the maximum slew rate for the plant temperature.
Tab. 5: Setting loop parameters
If appropriate, make sure to turn the Slew Rate Limit off when changing use case!

Power Limits

The User can limit the control power available to individual channels. To adjust control capacity from the Home screen, select CH X > Settings > Load Limits and the screen shown in figure 21 will appear.

Fig. 21: Screen for adjustment of control power capacity

Transducer and Thermistor

To set the properties of the transducer (TEC or heater) and thermistor for an individual channel from the Home screen, touch CH X > Settings > Plant. The menu in figure 22 will appear. Select TEC/Bipolar (as seen) or by touching TEC/Bipolar, select Heater/Unipolar.

From this screen, it is also possible to set the polarity of the TEC. Touch Polarity Positive/Polarity Negative to toggle between the two states. The polarity is already set correctly to POSITIVE for use with NTC thermistors.

The thermistor data has been configured at the factory for a typical NTC thermistor that is 10 kΩ at 25°C. Only NTC (Negative Thermal Coefficient) thermistors can be used. You can enter a new Beta value, reference temperature, and resistance value and the Steinhart-Hart constants will be calculated automatically or vice versa.

NOTE: The SLICE-QT can achieve sub-millikelvin stabilities over a very wide set point temperature range. For most applications working near room temperature, an NTC thermistor with a nominal value of 10 kΩ at 25°C will work fine. For temperatures far from room temperature, best results will occur by choosing a thermistor that has a resistance of 10 kΩ at your desired set point temperature. The input bridge circuitry is configured to have maximum sensitivity at a 10-kΩ resistance.

Fig. 22: Set Thermistor and Plant Information

WHEN USING A RESISTIVE HEATER, be sure to set the transducer type (CH X > Settings > Plant) to Heater/Monopolar. If set to TEC/Bipolar, attempts by the SLICE-QT to actively cool your plant will result in a thermal runaway condition.

Maximum & Minimum Temperature, Lock Range

The maximum and minimum allowable temperatures (Tmax and Tmin) can be set as well as the range of ∆T where the system is considered to be locked. From a Channel Detail screen (figure 17), tap Settings > Limits and the screen in figure 23 will appear. It is advised to set Tmin above the dew point temperature for your ambient conditions. If the temperature of the plant exceeds the range set by Tmax and Tmin, the temperature will be displayed in a flashing red field.

In the view shown, the lock range has been defined to be ±3 mK. If -3 mK ≤ ∆T ≤ +3 mK, ∆T will be displayed on a green field. If outside this range, ∆T will be displayed on a yellow field. The graph in the bottom right of the Channel Detail screen plots ∆T vs. time. The dashed yellow lines on this plot represent the lock range limits as set in this screen. Fig. 23: Screen for setting absolute extrema and lock range

Warning Window ºC Defines the nominal operating temperature range for the plant. When the actual temperature is within this window (±value), the temperature error will be displayed on a green background. When the error in the temperature is outside this window, the temperature error will be displayed on a yellow background.
Maximum Temp ºC Sets the maximum and minimum operating temperatures of the plant. The user will be prevented from adjusting the setpoint temperature to outside this range. If the actual temperature exceeds this range, the temperature will be displayed on a flashing red background.
Minimum Temp ºC
Tab. 6: Warning and Max/Min
If your plant is exposed to the atmosphere, use an abundance of caution in setting Tmin below the dew point for your ambient conditions! Water will condense on surfaces that are below the dew point temperature.

Front-panel Inputs & Outputs

Any input/output connections to the SLICE instrument must be derived from a Safety Extra Low Voltage (SELV) source.

The voltage range of the analog I/O on the SLICE-QT is ±10 V.

Input

The front panel of the SLICE-QT has two inputs (channels A & B) and two outputs (channels 1 & 2, not to be confused with the temperature control channels) available for use. To program their functionality, from any screen touch I/O. You will be presented with the screen shown in figure 24. Touch the Settings icon to the right of the channel you wish to program. If you select channel A input, you will be presented with the screen shown in figure 25. You can select the input to be any of the signals shown in table 7 for any of the four temperature-control channels.

Fig. 24: Programming the front-panel I/O

Fig. 25: Programming the input on Channel A Input

Choice Comment
Off Value not read
Slow Servo Input Control the servo output
External Set Point Adjust the set point temperature
External Error Input Alternate input path for error signal (bypasses wheatstone bridge)
Feed Forward Not currently implemented
Tab. 7: Front-panel input signals

Output

Similarly, you can program output values. If you select Channel 1 Output from figure 24 you will be presented with figure 26. You can choose any value from table 8 to be delivered to the Channel 1 Output output on the front panel.

Fig. 26: Programming the output on Channel 1 Output

Choice Comment
Off No data delivered to output channel
Temperature Actual temperature measured by thermistor
Temperature Error Temperature error ∆T = Tact - Tset: Actual temperature minus set point temperature
Current Output Current being delivered to specified temperature control channel
Tab. 8: Front-panel ouput signals

Triggering

External control of the SLICE-QT is accomplished via a TTL trigger.14) 0 to 0.8 V TTL is low and 2 to VCC is TTL high.

Trigger Out

The Trigger Out on the back panel of the SLICE-QT can be forced to go high to alert an external device to a status change. To program the trigger, from any screen touch I/O > Trigger Out. You will be presented with the screen shown in figure 27. Select those events on the desired channels for which you want the trigger to go high. A logical OR is performed on the set of selected events to determine the state of the output trigger. In the example, the trigger will go high if the minimum temperature set for CH 1 is exceeded, the maximum temperature set for CH 2 is exceeded, the maximum slew rate set for CH 3 is exceeded, or when CH 4 reaches its set point temperature.

Fig. 27: Programming the rear-panel trigger out

Trigger In

Currently, there are no input triggers allowed.

System Settings

Touching the System Settings button on the Control Bar (figure 9) will open the System Settings screen as seen in figure 28. Fig. 28: User-programmable system settings

User Interface Appearance

From this screen, adjustments to the brightness of the screen and the volume of the audio feedback can be made.

Input Impedance

Change the input impedance of the two front-panel input ports. Select either 50 Ω or 1 MΩ.

Firmware Version

Current firmware versions are reported here.

Host GUI

If accessed through a PC Host GUI, the Settings screen (figure 29) also has the ability to assign the COM port for the device. If viewed through the GUI, there are no brightness or volume controls as these should be set on the PC directly. Fig. 29: User-programmable system settings from host GUI

Servo/Manual Modes

Under most circumstances, the system will control the current to the transducer in order to minimize temperature fluctuations of your thermal plant. From time to time, it may also be desirable for the user to directly control the current to the transducer. This is done in Manual mode (open-loop control). To toggle between Servo and Manual modes, touch Servo on the Channel Detail screen (figure 17). In Servo mode (closed-loop control), it is possible to adjust the set point temperature, but not the current. In Manual mode, it is possible to adjust the current, but not the set point temperature. Caution should be exercised when using Manual mode as it is possible to create a thermal runaway condition where the transducer heats or cools without being limited.

In Manual mode, it may be possible for a thermal runaway condition to exist. Use caution when using Manual mode.

Using the Host GUI

It is possible to control the SLICE-QT from a Windows®-based PC using a GUI. In order to use the GUI, you must first download the latest version, connect the PC to the SLICE-QT, and assign a COM port to the SLICE-QT. The following describes the steps involved.

  1. Download and store the latest GUI executable from the FTP site (Request copy of executable GUI from sales [at] vescent [dot] com).
  2. Connect the SLICE-QT to the PC using a USB type B cable.
  3. Turn on the SLICE-QT.
  4. On the PC, double click on the SLICE-QT GUI to start the GUI.
  5. On your PC, go to Start > Control Panel > Device Manager > Ports
    1. Identify which COM Port is labeled “STMicroelectronics Virtual COM Port (COMXX)” or similar. Note the value of XX.
  6. On the SLICE-QT GUI, click on the Settings icon to get to the window shown in figure 30. Fig. 30: Settings screen when viewed by GUI
  7. Click on the OFF button below COM Port. You should see a menu similar to the one shown figure 31. NOTE: The COM port numbers may differ from those shown below. Fig. 31: COM port selection
  8. Select the COM port identified in the step above (usually the last COM port in the list; COM11 in this example). The window in figure 32 should appear if the connection is successful. Fig. 32: Ready to upgrade

The GUI should now actively control the SLICE-QT. You should only have to do the above steps once from a given PC. After assigning the COM port, the system will recognize the device in the future (unless you reassign the COM port to another device).

Firmware Update

From time to time, Vescent will upgrade the firmware for controlling the SLICE-QT. The procedure to upgrade the firmware is given here.

Serial API

It is possible to control the SLICE-QT through serial commands. More information coming soon. Please contact sales [at] vescent [dot] com for information.

Maintenance

There are no user-serviceable parts inside this instrument. Refer all repairs to the manufacturer. Work performed by persons not authorized by Vescent Photonics may void the warranty.

1)
More cables may be purchased separately
2)
Located in power receptacle on rear panel
3)
Subject to change without notice
4)
Lower precision may be realized above 50°C.  Consider using a thermistor with 10 kΩ at higher temperature than nominal.
5)
Nominal value 10 kΩ at room temperature. Precision at temperatures removed from room temperature can be improved by selecting a thermistor whose resistance is ~10 kΩ near the target temperature.
6)
Plant-dependent; value specified for D2-100 laser
7)
User-distributable over four channels
8)
Subject to 35 W overall maximum
9)
automatically adjusted
10)
See table 2 for acceptable input ranges
12)
In some early versions of the SLICE-QT, the order of these connectors is reversed.
13)
A usable discussion of the Ziegler-Nichols method can be found here: http://faculty.mercer.edu/jenkins_he/documents/TuningforPIDControllers.pdf
slice/qt.txt · Last modified: 2019/01/21 17:42 by Kurt Vogel