THORLABS MDT693B User manual

MDT693B and MDT694B
Open-Loop
Piezo Controllers
User Guide

Open-Loop Piezo Controllers
Table of Contents
Chapter 1 Warning Symbol Definitions ............................................................................................ 1
Chapter 2 Safety.............................................................................................................................. 2
Chapter 3 Description...................................................................................................................... 3
Chapter 4 Setup………………………………………………..................................................................... 4
4.1. Setting AC Line Voltage and Fuses..............................................................................................4
4.2. Changing Fuses..............................................................................................................................4
4.3. List of Contents ..............................................................................................................................4
4.4. Initial Setup .....................................................................................................................................4
Chapter 5 Operation........................................................................................................................ 5
5.1. MDT693B Front Panel Overview ...................................................................................................5
5.2. MDT693B Back Panel Overview....................................................................................................5
5.3. MDT694B Front Panel Overview ...................................................................................................6
5.4. MDT694B Rear Panel Overview.....................................................................................................6
5.5. Setting the Output Voltage Limit ..................................................................................................7
5.6. Using INT Adjustment Knob..........................................................................................................7
5.7. Using EXT Input BNC.....................................................................................................................8
5.8. Master Scan Control (MDT693B Only)..........................................................................................8
Chapter 6 Bandwidth Performance ................................................................................................ 10
6.1. Low-Pass Filter.............................................................................................................................10
6.2. Output Current Limit ....................................................................................................................10
Chapter 7 Remote Communications .............................................................................................. 12
7.1. Installing USB Drivers..................................................................................................................12
7.2. Command-Line Interface .............................................................................................................12
7.3. Keywords (Commands and Queries) .........................................................................................13
Chapter 8 Specifications ............................................................................................................... 15
Chapter 9 Mechanical Drawings..................................................................................................... 17
9.1.MDT693B Mechanical Drawing....................................................................................................17
9.2. MDT694B Mechanical Drawing....................................................................................................17
Chapter 10 Troubleshooting............................................................................................................ 18
Chapter 11 Warranty ....................................................................................................................... 19
Chapter 12 Regulatory .................................................................................................................... 20
12.1. Waste Treatment is Your Own Responsibility...........................................................................20
12.2. Ecological Background................................................................................................................20
Chapter 13 Certifications and Compliance....................................................................................... 21
Chapter 14 Thorlabs Worldwide Contacts........................................................................................ 23

Open-Loop Piezo Controllers Chapter 1: Warning Symbol Definitions
Rev F, April 12, 2023 Page 1
Chapter 1 Warning Symbol Definitions
Below is a list of warning symbols you may encounter in this manual or on your device.
Symbol
Description
Direct Current
Alternating Current
Both Direct and Alternating Current
Earth Ground Terminal
Protective Conductor Terminal
Frame or Chassis Terminal
Equipotentiality
On (Supply)
Off (Supply)
In Position of a Bi-Stable Push Control
Out Position of a Bi-Stable Push Control
Caution: Risk of Electric Shock
Caution: Hot Surface
Caution: Risk of Danger
Warning: Laser Radiation
Caution: Spinning Blades May Cause Harm

Open-Loop Piezo Controllers Chapter 2: Safety
Page 2 TTN011225-D02
Chapter 2 Safety
All statements regarding safety of operation and technical data in this instruction manual will only apply when the
unit is operated correctly.
SHOCK WARNING
HIGH VOLTAGE
To avoid electrical shock and before applying power to your MDT693B or MDT694B system, make
sure that the protective conductor of the 3-conductor mains power cord is correctly connected to
the protective earth contact of the socket outlet!
Improper grounding can cause electric shock resulting in severe injury or even death.
Do not operate without the cover installed. Refer servicing to qualified personnel.
WARNING –HIGH VOLTAGE OUTPUTS
The MDT693B and MDT694B can produce hazardous voltages and currents. Use CAUTION when
operating the MDT693B or MDT694B and handling the piezo actuators! The piezo elements are
electrical capacitors capable of storing electrical energy over long periods of time. Besides storing
charge from the MDT693B or MDT694B, the piezo can accumulate static charge over time due to
varying storage temperature and/or mechanical loads. To safely discharge a piezo, connect it to the
MDT693B or MDT694B and set the output voltage to 0 volts.
WARNING
This unit must not be operated in explosive environments.
ATTENTION
Do not obstruct the air ventilation slots in the housing or fan exhaust.
WARNING
Before applying power to your MDT693B or MDT694B system, make sure that the protective
conductor of the 3-conductor mains power cord is correctly connected to the protective earth
contact of the socket outlet! Improper grounding can cause electric shock resulting in severe injury
or even death.
With the exception of the mains fuses, there are no user-serviceable parts in this product.
This device can only be returned when packed into the complete original packaging, including all foam packing
inserts. If necessary, ask for a replacement package.
Mobile telephones, cellular phones, or other radio transmitters are not to be used within the range of three meters
of this unit since the electromagnetic field intensity may exceed the maximum allowed disturbance values
according to EN50082-1.

Open-Loop Piezo Controllers Chapter 3: Description
Rev F, April 12, 2023 Page 3
Chapter 3 Description
The MDT693B and MDT694B are precision, low-noise, low-drift, high-voltage controllers for piezo actuators. They
provide both local and remote control of piezo drive voltages. The MDT694B supports one channel, while the
MDT693B supports up to three channels. They are well suited for single-axis and multiple-axis piezo stages, such
as Thorlabs’ MAX312D Three-Axis NanoMax Stage and PE4 Piezoelectric Actuator. Typical applications include
remote alignment of single-mode fiber couplers, high-resolution translation, microscopy, and remote positioning.
The intelligent-speed-control potentiometers on the front panel allow for precise setting of the output voltage over
the full operating range. This fine control takes full advantage of the inherently high resolution of the piezo
element. The MDT693B three-channel controller provides independent controls for each channel.
The drive voltage can also be controlled externally through a USB interface or by applying an analog voltage (0 to
10 V) to the EXT BNC input on the front panel. This voltage is summed with the manual control voltage and
multiplied by a gain of 15 V/V.
  󰇛󰇜󰇛󰇜
The external control voltage can be supplied by any stable voltage source, including function generators, DAC
outputs, or DC supplies. In addition, the external voltage can be used as part of a feedback loop for automated
alignment systems. Since the external input voltage is summed with either the manual or the USB voltage setting,
the manual/USB control can be used for offset adjustments without having to re-adjust the external voltage
source.
The MDT693B and MDT694B include a voltage limit switch on the rear panel to select the operating voltage
range and gain for the unit. Each unit is shipped with the voltage limit set for 0 - 75 V (Gain = 7.5 V/V) operation
and may be adjusted by the user to provide 0 - 100 V (Gain = 10 V/V) or 0 - 150 V (Gain = 15 V/V) operation.
The Master Scan feature on the MDT693B allows all three channels to be controlled by one manual adjuster or
one external control signal. In this mode, each channel can be precisely adjusted by an offset voltage (INT control
knob for each axis) and by a gain adjustment (SCAN TRIM adjustment for each channel). The gain adjustment
allows the output for each channel to be amplified from 80 to 120% of the master control signal.
The MDT693B and MDT694B include 4-digit LED readouts for displaying real-time output voltages of all
channels.
These controllers contain a universal power supply. At the time of order, a power cord specific to the region from
which your order originates will be included in the box. Should you need a power cord for a different region,
please contact your local Thorlabs Tech Support.

Open-Loop Piezo Controllers Chapter 4: Setup
Page 4 TTN011225-D02
Chapter 4 Setup
4.1. Setting AC Line Voltage and Fuses
The MDT693B and MDT694B piezo controllers are shipped configured for 100 to 240 VAC operation. There is no
end-user adjustment of the line voltage. Simply select the correct AC line cord for their geographic location.
4.2. Changing Fuses
To change the power fuse, perform the following steps:
1. Remove the AC line cord if it is connected to the unit.
2. Locate the fuse tray directly below the AC line cord connection on the rear panel of the unit.
3. Carefully use a flat blade screwdriver to open the fuse tray.
4. Remove the existing fuse and install the appropriate fuse (600 mA for the MDT693B, 500 mA for the
MDT694B). The replacement fuse must be a 5 mm x 20 mm, 250 VAC Type T Fuse (IEC 60127-2/III, low
breaking capacity, slow blow).
5. Push the fuse tray back into place, making sure that it snaps and seats correctly.
6. Connect the appropriate line cord into the AC receptacle and plug the unit in.
4.3. List of Contents
1. MDT693B or MDT694B Controller
2. BNC to SMC Adapter (3 Included with MDT693B, 1 Included with MDT694B)
3. USB Type A to Type B Cable
4. Power Cord (Determined by the Region the Order was Placed From)
5. Operating Manual
4.4. Initial Setup
1. Carefully unpack the controller and accessories. If any of the items appear damaged or missing, do not
use the controller. Contact your local Thorlabs tech support for assistance.
2. Make sure the POWER switch located on the front panel is in the OFF position.
3. Plug the female end of the provided AC line cord into the AC input receptacle on the rear of the unit. Plug
the male end into a properly grounded AC socket.
4. Select the appropriate output voltage limit on the rear panel. The user can choose from 75 V (Gain =
7.5 V/V), 100 V (Gain = 10 V/V), or 150 V (Gain = 15 V/V) limits.
This switch should only be adjusted while the piezo(s) are disconnected or when the unit is off.
5. Connect the piezo device to the controller output(s). Do not connect piezo devices to the unit while the
unit is on.
6. Turn the POWER switch to the ON position.
7. Push and turn the INT control knob to adjust the piezo output voltage. For more advanced controls such
as the external input, master scan controls, or USB operation, please see the Table of Contents for the
appropriate section of this manual. Note: The Push to adjust requirement can be disabled with the
command “pushdisable=1”, when disabled the output will be adjusted with any rotation of the
knob and the right-most decimal will no longer blink.

Open-Loop Piezo Controllers Chapter 5: Operation
Rev F, April 12, 2023 Page 5
Chapter 5 Operation
5.1. MDT693B Front Panel Overview
5.2. MDT693B Back Panel Overview
7-Segment LED
4 Digits
INT Control Knob
Voltage
Adjustment
Scan Trim
Gain
Adjuster
80% - 120%
Master EX T Input
Modulation Input
0 –10 V
Enable Switch/LED
Enables Master Scan
LED On When Enabled
Power
Switch
Turns Unit
On and Off
AC Input
IEC320
Connector
Fan
Fan with Guard
Model
Serial
Number
Voltage Limit
Switch
Sets Output
Voltage Limit
Communication
USB-B 2.0
HV Output
3 Channel Output
CAUTION: High
Voltage
EXT Input
Modulation Input
0 –10 V
Master INT
Master Voltage
Adjust

Open-Loop Piezo Controllers Chapter 5: Operation
Page 6 TTN011225-D02
5.3. MDT694B Front Panel Overview
5.4. MDT694B Rear Panel Overview
7-Segment LED
4 Digits
INT Control Knob
Voltage
Adjustment
Power
Switch
Turns Unit
On and Off
AC Input
IEC320
Connector
Fan
Fan with Guard
Model
Serial
Number
Voltage Limit Switch
Sets Output
Voltage Limit
Communication
USB-B 2.0
HV Output
1 Channel Output
CAUTION: High
Voltage
EXT Input
Modulation Input
0 –10 V

Open-Loop Piezo Controllers Chapter 5: Operation
Rev F, April 12, 2023 Page 7
5.5. Setting the Output Voltage Limit
The MDT693B and MDT694B include a voltage limit switch on the rear panel that can be used to limit the
maximum output voltage to 75 V, 100 V, or 150 V. The lower limit is intended for lower-drive-voltage piezos.
Thorlabs ships the controllers to operate at the 75 V limit by default. However, it can be easily adjusted, as
described below:
1. Determine the maximum allowable voltage for your piezo element (VPIEZO). We recommend the following
settings:
a. Use the 150 V limit when VPIEZO ≥150 V.
b. Use the 100 V limit when 150 V ≥VPIEZO ≥100 V.
c. Use the 75 V limit when 100 V ≥VPIEZO ≥75 V.
2. Power off the MDT693B or MDT694B and disconnect the piezo(s).
3. Locate the Voltage Limit switch on the rear panel of the MDT693B or MDT694B.
4. Adjust the switch to the desired limit setting determined in Step 1.
5. Turn the controller on. The onboard micro controller will automatically configure the controller to the
appropriate settings. The gain of the EXT input BNC connector(s) will vary depending on the gain setting.
For the 150 V limit, the gain is 15 V/V; for the 100 V setting, the gain is 10 V/V; and for the 75 V setting,
the gain is 7.5 V/V.
5.6. Using INT Adjustment Knob
The INT adjustment knobs manually control the output voltages for each channel from 0 V to 150 V. This can be
thought of as a DC offset voltage, since it is summed with the external control voltage (up to a maximum control
voltage of 10 V). Note that changing the voltage through USB commands overrides the INT knob.
By default all adjustment knobs include a lockout feature to prevent accidental adjustment. To adjust the voltage
setting, the knob must first be pushed in to unlock it. On the corresponding display, the right-most decimal point
will blink after the knob is pushed in, indicating that it is ready for adjustment. To lock the setting, press the knob
in again. The knob will automatically relock after 30 seconds of no activity. Note: The Push to adjust
requirement can be disabled with the command “pushdisable=1”, when disabled the output will be
adjusted with any rotation of the knob and the right-most decimal will no longer blink.
The manual adjustment knobs are auto scaling: Adjusting the knob slowly will adjust the output at the highest
resolution, and adjusting the knob quickly will make larger voltage adjustments.
Follow the procedure described on the next page for operation in this mode.
1. Attach a piezo to one of the high voltage output connectors on the rear panel of the MDT693B or the front
panel of the MDT694B.
Note: The BNC center conductor is positive and the shield is at ground potential. Be certain to
match piezo polarity to the connector since most piezo elements will be permanently damaged if
connected backwards.
2. Turn the power switch (located on the front panel) to the ON position. The digital displays should begin
displaying the output voltage settings. The factory default output setting is 0 V. The unit recalls the
previous output state when it is powered on.
3. Set all the output voltages to 0 V by pushing in the control knob and rotating the knob counter-clockwise.
The right-most decimal point will blink after the knob is pushed in, indicating that the setting can be
adjusted. After 30 seconds of no activity, the display will stop blinking. Note: The Push to adjust
requirement can be disabled with the command “pushdisable=1”, when disabled the output will
be adjusted with any rotation of the knob and the right-most decimal will no longer blink.
4. Adjust the INT knob for each channel until the desired voltages are met.

Open-Loop Piezo Controllers Chapter 5: Operation
Page 8 TTN011225-D02
5.7. Using EXT Input BNC
The EXT input on the MDT693B and MDT694B is designed to allow the user to modulate the output voltage or for
use as feedback with positioning systems. Examples of connections for this input include D/A systems, strain
gauges with support electronics, and function generators. The external control voltage is summed with either the
INT control knob or the USB voltage setting (changing the voltage through USB will override the INT knob), up to
a maximum control voltage of 10 V. To use this feature, follow the steps below.
1. Attach a piezo to one of the high voltage output connectors on the rear panel of the MDT693B or the front
panel of the MDT694B.
Note: The BNC center conductor is positive and the shield is at ground potential. Be certain to
match piezo polarity to the connector since most piezo elements will be permanently damaged if
connected backwards.
2. Turn the power switch to the ON position.
3. Set all the output voltages to 0 V by pushing in the control knob and rotating the knob counter-clockwise.
The right-most decimal point will blink after the knob is pushed in, indicating that the setting can be
adjusted. After 30 seconds of no activity, the display will stop blinking. Note: The Push to adjust
requirement can be disabled with the command “pushdisable=1”, when disabled the output will
be adjusted with any rotation of the knob and the right-most decimal will no longer blink.
4. Connect an analog input signal (AC or DC), with a voltage between 0 V and 10 V, to the EXT input BNC
connector(s). The output for each channel will follow the EXT input voltage with a gain of 7.5 V/V, 10 V/V,
or 15 V/V, depending upon the output voltage limit (see Section 5.5, page 7).
Note: Do not place a negative voltage on the EXT input BNC connector. The MDT693B and
MDT694B include reverse protection diodes on the EXT inputs, designed to prevent the piezo
output from going negative. Presenting negative voltages for long periods of time will damage
these diodes and affect the operation of the unit.
5. For sinusoidal and ramp signals, calculate the output current and verify that it will not exceed the
maximum current rating of 60 mA. A piezo acts like a capacitor; therefore the output current is a function
of the change in voltage divided by the change in time. The MDT693B and MDT694B both have an
output-current-limiting circuit to prevent damage to the unit, but the output sinusoid will be distorted.
5.8. Master Scan Control (MDT693B Only)
The Master Scan feature allows all three channels to be controlled by one manual adjuster or one external control
signal. Each channel has an independent gain adjustment (SCAN TRIM) that allows the user to compensate for
differences between each piezo. The output of each channel is summed with the INT control knobs to provide a
different DC offset for each channel.
The Master Scan mode is especially useful for three-axis mounts such as the MAX312D. The SCAN TRIM gain
controls and the INT knobs allow the user to precisely tune each output separately, while the MASTER SCAN INT
and MASTER SCAN EXT controls adjust all channels simultaneously.
Enable Button
The ENABLE button located on the front panel (see Section 5.1, page 5) is used to enable and disable Master
Scan mode. The EXT in for each channel will be disabled and replaced by the master scan EXT signal.
Enable LED
The enable LED, located directly above the ENABLE button, will light when Master Scan mode is activated.
Master Scan EXT
An analog voltage between 0 V and 10 V can be applied to this input to control all three channels over a voltage
range of 0 V to 75 V, 0 V to 100 V, or 0 V to 150 V. This input will be summed with the MASTER SCAN INT and
the individual INT knobs for each channel, up to a maximum control voltage of 10 V. The MASTER SCAN EXT

Open-Loop Piezo Controllers Chapter 5: Operation
Rev F, April 12, 2023 Page 9
input is only active when Master Scan mode is active (i.e., the enable LED must be lit). Note that the individual
EXT in for each channel is disabled when Master Scan mode is active.
Master Scan INT
The MASTER SCAN INT knob allows adjustment of all three channels over the full operating range of 0 V to
75 V, 0 V to 100 V, or 0 V to 150 V. This input will be summed with the MASTER SCAN EXT and the individual
INT knobs for each channel, up to a maximum control voltage of 10 V. The MASTER SCAN INT knob will only be
active when Master Scan mode is active (i.e., the enable LED must be lit).
Master Scan Trim
The SCAN TRIM adjusters scale the signals provided by the MASTER SCAN INT and MASTER SCAN EXT
knobs over a range from 80% to 120% on a per-channel basis. This helps compensate for differences in
reactance from one piezo to another. The SCAN TRIM adjusters are only active when Master Scan mode is
active (i.e., the enable LED must be lit).
Note: The 100% mark is halfway through the adjustment range of the SCAN TRIM potentiometer. To
approximately set the SCAN TRIM to 100%, zero the pot by turning it counterclockwise as far as possible
(a maximum of four turns). Then adjust the pot clockwise by two turns.
To precisely set the SCAN TRIM to 100%, follow this procedure:
•Adjust all of the INT control knobs counterclockwise as far as possible.
•Disconnect any EXT input connections.
•Adjust all SCAN TRIM pots counterclockwise by a minimum of four turns.
•Apply a 5 V DC voltage source to the MASTER SCAN EXT input.
•Adjust the SCAN TRIM pots clockwise until their displays read 75 V (assuming the voltage limit is set to
150 V).

Open-Loop Piezo Controllers Chapter 6: Bandwidth Performance
Page 10 TTN011225-D02
Chapter 6 Bandwidth Performance
The MDT693B and MDT694B are precision, low-noise, low-drift, high-voltage amplifiers designed specifically for
driving piezo actuators. There are two limitations that need to be considered. Since piezoelectric crystals can be
modeled as capacitors, it is easy to predict their dynamic performance using a basic set of equations as described
below.
6.1. Low-Pass Filter
Since the piezo can be modeled most accurately as a capacitor, the piezo will create a low-pass filter with the
output impedance of the driver. For both the MDT693B and MDT694B, the output impedance is specified as
150 , 1 nF.
 
󰇛󰇜
Where,
   
For example, consider connecting a piezo with a 1.6 F capacitance to the MDT693B. Using the output
impedances given in the specification section (see page 15):
 
󰇛󰇜󰇛 󰇜
 
6.2. Output Current Limit
The output current limit also needs to be considered when determining system performance. Since the piezo is
electrically equivalent to a capacitor (CPIEZO), the charge rate (∆V/∆t) needs to be considered. The max current for
the MDT693B and MDT694B is 60 mA (IOUT).
   

The output current requirements depend upon how quickly the piezo needs to be charged, not the voltage applied
to it. Below are some common waveforms and their calculations.

Open-Loop Piezo Controllers Chapter 6: Bandwidth Performance
Rev F, April 12, 2023 Page 11
Linear Ramp Signal
  

  󰇛󰇜
 
Triangle Wave
  

  󰇛󰇜
 
  

Sinusoid Wave
  󰇛󰇜
󰇛󰇜  
  

Where
   󰇛󰇜and   
For all equations above,
   

Open-Loop Piezo Controllers Chapter 7: Remote Communications
Page 12 TTN011225-D02
Chapter 7 Remote Communications
7.1. Installing USB Drivers
Prior to running the command-line interface, the USB drivers must be installed. To install the drivers the user
must have administrative rights on the computer. The MDT693B and MDT694B must not be connected to
the PC while installing the drivers. Refer to the link provided on the Download Card that was included with your
unit, or by visiting https://www.thorlabs.com/manuals.cfm to download and install the latest software for the
MDT693B or MDT694B. From the dialog box that is displayed, select the Install Drivers button. Follow the
onscreen prompts to install the driver. After the driver is installed, attach the MDT693B or MDT694B to the PC
and power it on. Your PC will then detect the new hardware and will prompt you when the installation is complete.
7.2. Command-Line Interface
Once the USB drivers have been installed, the unit connected to the PC, and the power turned on, configure the
terminal emulator as follows:
•Baud Rate = 115.2 kb/s
•Data Bits = 8
•Parity = None
•Stop Bits = 1
•Flow Control = None
If the connection is correct you will see the following after pressing the “Enter” key.
CMD_NOT_DEFINED>
The basic structure of the interface is a keyword followed by either an equals sign “=” or a question mark “?”. The
“=” or “?” will determine if the string is a command or a query. All strings (commands and queries) must be
terminated by a carriage return (CR) or a line feed (LF) or any combination of a carriage return and a line feed or
pressing the ENTER key on the computer.
The command structure is as follows:
Keyword = argument (Command Terminator)
Where “keyword” defines the function and “argument” is a numerical value followed by any valid command
terminator. A valid command terminator is a carriage return (CR), a line feed (LF) or any combination of a carriage
return and line feed. See listing below.
The query structure is a follows:
Keyword? (Command Terminator)
The “keyword” defines the function and the question mark (?) indicates a query. The query is terminated by any
valid command terminator. A valid command terminator is a carriage return (CR), a line feed (LF) or any
combination of a carriage return and line feed. See listing below.
There are a few exceptions to this which are noted below, also noted are unique shortcut keys.
The prompt symbol “>” will appear on power up and after a command is accepted by the system indicating it is
ready to receive another command line.

Open-Loop Piezo Controllers Chapter 7: Remote Communications
Rev F, April 12, 2023 Page 13
7.3. Keywords (Commands and Queries)
The following list shows all available commands and queries, and summarizes their functions for the MDT693B:
Command1
Syntax2
Description
Get Commands
?
List the available commands.
Product Information
id?
Returns the product header and firmware version
Restore Default Settings
restore
Restores default factory settings
Get Echo Command Value
echo?
Returns echo status
Set Echo Command
echo=n
Sets Echo mode. When the echo mode is on the command parameters will be
returned, or echoed back, to the communication program. (Values: 1 = enable; 0
= disable)
Limit Switch Setting
vlimit?
Returns output voltage limit setting. (75V = 0; 100V = 1; 150V = 2)
Get Display Intensity
intensity?
Returns the display intensity
Set Display Intensity
intensity=n
Set the Display Intensity (0-15).
Set All Voltages
allvoltage=n
Sets all outputs to desired voltage.
Get Master Scan Enable
msenable?
Returns the state of the Master Scan enable.
Set Master Scan Enable
msenable=n
Sets Master Scan mode. (Values: 1 = enable; 0 = disable)
Get Master Scan Voltage
msvoltage?
Reads and Returns the master scan voltage
Set Master Scan Voltage
msvoltage=n
Sets a master scan voltage that adds to the x, y, and z axis voltages. (Sets
master scan DAC)
Read X-Axis Voltage
xvoltage?
Reads and returns the X axis output voltage.
Set X-Axis Voltage
xvoltage=n
Set the output voltage for the X axis.
Read Y-Axis Voltage
yvoltage?
Reads and returns the Y axis output voltage.
Set Y-Axis Voltage
yvoltage=n
Set the output voltage for the Y axis.
Read Z-Axis Voltage
zvoltage?
Reads and returns the Z axis output voltage.
Set Z-Axis Voltage
zvoltage=n
Set the output voltage for the Z axis.
Read Min. X-Axis Voltage
ymin?
Reads the minimum output voltage limit for X axis.
Set Min. X-Axis Voltage
xmin=n
Sets the minimum output voltage limit for X axis.
Read Min. Y-Axis Voltage
ymin?
Reads the minimum output voltage limit for Y axis.
Set Min. Y-Axis Voltage
ymin=n
Sets the minimum output voltage limit for Y axis.
Read Min. Z-Axis Voltage
zmin?
Reads the minimum output voltage limit for Z axis.
Set Min. Z-Axis Voltage
zmin=n
Sets the minimum output voltage limit for Z axis.
Read Max. X-Axis Voltage
xmax?
Reads and returns the maximum output voltage limit for X axis.
Set Max. X-Axis Voltage
xmax=n
Sets the maximum output voltage limit for X axis.
Read Max. Y-Axis Voltage
ymax?
Reads and returns the maximum output voltage limit for Y axis.
Set Max. Y-Axis Voltage
ymax=n
Sets the maximum output voltage limit for Y axis.
Read Max. Z-Axis Voltage
zmax?
Reads and returns the maximum output voltage limit for Z axis.
Set Max. Z-Axis Voltage
zmax=n
Sets the maximum output voltage limit for Z axis.
Get voltage adjustment resolution
dacstep?
Reads the current step resolution
Set voltage adjustment resolution
dacstep=n
Sets the step resolution when using up/down arrow keys
(n = 1 to 1000)
Increment Voltage
Up arrow
Increments the current channel voltage by resolution set in dacsteps
(Adjustment range: 0 to 65536, limited by factory calibrated limit)
Decrement Voltage
Down arrow
Decrements the current channel voltage by resolution set in dacsteps
(Adjustment range: 0 to 65536, limited by factory calibrated limit)
Decrease channel
Left arrow
Decreases channel setting and returns value (order: master scan if enabled, z
axis, y axis, x axis)
Increase channel
Right arrow
Increases channel setting and returns value (order: master scan if enabled, z
axis, y axis, x axis)
Get Friendly Name
friendly?
Returns the friendly name.
Set Friendly Name
friendly=string
Sets the friendly name.
Get Serial Number
serial?
Returns the serial number.
Get Compatibility Mode
cm?
Returns compatibility mode (0 = disabled, 1 = enabled)
Set Compatibility Mode
cm=n
Sets compatibility mode (0 = disable, 1 = enable)
Get Rotary Mode
rotarymode?
Returns the rotary controls mode. (0 = Default, 1 = 10 turn pot, 2 = fine)
Set Rotary Mode
rotarymode=
Sets the rotary controls mode. (0 = Default, 1 = 10 turn pot, 2 = fine)
Get disable rotary push to adjust
disablepush?
Gets the disable rotary push to adjust requirement setting.
(0 = push required, 1 = push not required)
Set disable rotary push to adjust
disablepush=
Returns the disable rotary push to adjust requirement setting.
(0 = push required, 1 = push not required)
1
All commands and queries are not case sensitive.
2
The MDT693B will recognize MDT693A commands.

Open-Loop Piezo Controllers Chapter 7: Remote Communications
Page 14 TTN011225-D02
The following list shows all available commands and queries, and summarizes their functions for the MDT694B:
Command3
Syntax4
Description
Get Commands
?
List the available commands.
Product Information
id?
Returns the product header and firmware version
Restore Default Settings
restore
Restores default factory settings
Get Echo Command Value
echo?
Returns echo status
Set Echo Command
echo=n
Sets Echo mode. When the echo mode is on the command parameters will be
returned, or echoed back, to the communication program. (Values: 1 = enable;
0 = disable)
Limit Switch Setting
vlimit?
Returns output voltage limit setting. (75V = 0; 100V = 1; 150V = 2)
Get Display Intensity
intensity?
Returns the display intensity
Set Display Intensity
intensity=n
Set the Display Intensity (0-15).
Read X-Axis Voltage
xvoltage?
Returns the X axis output voltage.
Set X-Axis Voltage
xvoltage=n
Set the output voltage for the X axis.
Read Min. X-Axis Voltage
Xmin?
Returns the minimum output voltage limit for X axis.
Set Min. X-Axis Voltage
xmin=n
Sets the minimum output voltage limit for X axis.
Read System Min. Voltage
sysmin?
Returns the minimum output voltage for the system.
Set System Min. Voltage
sysmin=n
Sets the minimum output voltage for the system.
Read Max. X-Axis Voltage
Xmax?
Returns the maximum output voltage limit for X axis.
Set Max. X-Axis Voltage
xmax=n
Sets the maximum output voltage limit for X axis.
Read System Max. Voltage
sysmax?
Returns the maximum output voltage for the system.
Set System Max. Voltage
sysmax=n
Sets the maximum output voltage for the system.
Get voltage adjustment resolution
dacstep?
Reads the current step resolution
Set voltage adjustment resolution
dacstep=n
Sets the step resolution when using up/down arrow keys
(n = 1 to 1000)
Increment Voltage
Up arrow
Increments the current channel voltage by resolution set in dacsteps
(Adjustment range: 0 to 65536, limited by factory calibrated limit)
Decrement Voltage
Down arrow
Decrements the current channel voltage by resolution set in dacsteps
(Adjustment range: 0 to 65536, limited by factory calibrated limit)
Get Friendly Name
friendly?
Returns the friendly name.
Set Friendly Name
friendly=string
Sets the friendly name.
Get Serial Number
serial?
Returns the serial number.
Get Compatibility Mode
cm?
Returns compatibility mode (0 = disabled, 1 = enabled)
Set Compatibility Mode
cm=n
Sets compatibility mode (0 = disable, 1 = enable)
Get Rotary Mode
rotarymode?
Returns the rotary controls mode. (0 = default, 1 = 10 turn pot, 2 = fine)
Set Rotary Mode
rotarymode=
Sets the rotary controls mode. (0 = default, 1 = 10 turn pot, 2 = fine)
Get disable rotary push to adjust
disablepush?
Returns the disable rotary push to adjust requirement setting.
(0 = push required, 1 = push not required)
Set disable rotary push to adjust
disablepush=
Sets the disable rotary push to adjust requirement setting.
(0 = push required, 1 = push not required)
If the keyword, format, or argument is incorrect or out of range, the unit will return an exclamation point. The
function is determined by the value set with the mode command in the above table.
In addition to the above commands, there is also special functionality added to the arrow keys of the computer’s
keyboard.
3
All commands and queries are not case sensitive.
4
The MDT694B will recognize MDT694A commands.

Open-Loop Piezo Controllers Chapter 8: Specifications
Rev F, April 12, 2023 Page 15
Chapter 8 Specifications
All specifications are for both MDT693B and MDT694B unless noted explicitly.
General Features
Parameter
MDT693B
MDT694B
AC Input Voltage
100 - 240 VAC
AC Input Frequency
50 - 60 Hz
AC Input Power (Max)
60 VA
30 VA
Operating Temperature
10 to 40 °C
Fuse Type
IEC60127-2/3 (250 VA, Slow Blow Type ‘T’)
Fuse Size
5 mm x 20 mm
Fuse Rating
600 mA
500 mA
Performance
Input/Output Specs
External Input Voltage
0 - 10 V
External Input Impedance
10 kΩ
Output Voltage
0 - 75, 0 - 100, or 0 - 150 VDC
(Limit Switch Dependent)
Output Current Limit (Max)
60 mA
Output Noise5
1.5 mVrms (~9.9 mVpp)
Output Impedance (Max)
150 Ω, 1.0 nF
Min Load Impedance6
2.5 kΩ
Output Voltage Range (Switch Selectable)
Voltage Limit Position (75 V)
0 - 75 VDC
Voltage Limit Position (100 V)
0 - 100 VDC
Voltage Limit Position (150 V)
0 - 150 VDC
External Input Gain
Voltage Limit Position (75 V)
7.5 V/V (±5%)
Voltage Limit Position (100 V)
10 V/V (±5%)
Voltage Limit Position (150 V)
15 V/V (±5%)
Scan Trim Gain Adjustment
80% to 120% of Master Scan Ext + Int
Bandwidth (-3 dB)
No Load, Small Signal7
9 kHz
No Load, 150 Vpp7
8.5 kHz
1.4 µF Piezo, 150 Vpp
200 Hz
Stability
<0.01% over 5 hours
A/D and D/A Performance
D/A Resolution
16-Bit / 2.75 mV
A/D Resolution
16-Bit / 3.0 mV
Communications
USB 2.0
5
The MDT693B and MDT694B were tested without an external load connected (1 nF output impedance only). Adding a capacitive load, such
as a piezo, will decrease the noise spec since the capacitance will create a low-pass filter with the output resistance.
6
The Min Load Impedance represents the smallest allowable terminating resistance. Applying lower impedances will cause the short-circuit
protection to limit the output voltage. Continued use in this mode will cause circuit degradation and eventual circuit failure.
7
Assume a ramp function is used. The bandwidth is load-dependent and requires calculation for a more representative number. See Chapter
6, page 10 for details.

Open-Loop Piezo Controllers Chapter 8: Specifications
Page 16 TTN011225-D02
Connections and Controls
Interface Control
Optical Encoder with Push Button
Display
4-Digit, 7-Segment LED
Input Power Connection
IEC Connector
Input/Output Connectors
BNC (Male)
Power On
Rocker Switch
Scan Trim Controls
4-Turn Potentiometer
Remote Interface
USB Type B
Physical Specifications
Parameter
MDT693B
MDT694B
Display Type
7-Segment LED with 4 Digits
Display Resolution
0.1 V
Number of Displays
3
1
Number of Channels
3
1
Dimensions
12.18" x 4.15" x 8.55"
(309.4 x 105.5 x 217.1 mm)
6.05" x 3.22" x 12.11"
(153.6 x 81.8 x 307.6 mm)
Weight
3.02 kg (6.65 lbs)
1.93 kg (4.25 lbs)

Open-Loop Piezo Controllers Chapter 9: Mechanical Drawings
Rev F, April 12, 2023 Page 17
Chapter 9 Mechanical Drawings
9.1. MDT693B Mechanical Drawing
9.2. MDT694B Mechanical Drawing

Open-Loop Piezo Controllers Chapter 10: Troubleshooting
Page 18 TTN011225-D02
Chapter 10 Troubleshooting
The following table describes some typical problems that may be encountered while using the MDT69xB and
possible solutions to these problems.
Problem
Solution
Unit does not turn on when switching the
power switch to the ON position.
1. Make sure the AC line cord is fully inserted into the AC input receptacle
and plugged into an outlet providing 100 to 240 VAC.
2. Fuse(s) may be open. Refer to Section 4.2 for information on replacing
open fuses. If the problem persists, please return the unit to Thorlabs
for evaluation.
I cannot adjust the voltage.
1. Make sure the correct channel is selected. Adjust the voltage by
pushing in the INT knob. Adjustment can only occur when the display
is blinking.
I can’t connect to the MDT693B/MDT694B
over the USB port.
1. Make sure the unit is turned on prior to connecting the USB.
2. Power off unit, remove AC cord, remove the USB cable, reattach AC
cord, power on unit and reattach the USB cable.
3. Make sure USB drivers are installed.
The output voltage is 0 V even when
adjusting.
1. Turn the power off.
2. Unplug your piezo device.
3. Turn the unit back on and retest.
4. Piezos tend to fail as a short circuit, causing the output current limit
protection circuit to attenuate the output.