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Summary of Contents for THORLABS DSC1
- Page 1 DSC1 Compact Digital Servo Controller User Guide...
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Page 2: Table Of Contents
Chapter 2 Safety ......................... 3 Chapter 3 Installation ......................... 4 3.3.1 Basics ................................... 4 3.3.2 Ground Loops and the DSC1 ..........................4 3.3.3 Powering the DSC1 .............................. 5 Chapter 4 Operation ........................5 4.1.1 Launching the Touchscreen Interface ......................... 5 4.1.2... - Page 3 Compact Digital Servo Controller Chapter 6 Maintenance and Cleaning ..................23 Chapter 7 Troubleshooting and Repair ..................23 Chapter 8 Disposal ........................23 Chapter 9 Thorlabs Worldwide Contacts ................... 24...
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Page 4: Chapter 1 Introduction
Introduction Intended Use The DSC1 is a compact digital servo controller designed for general laboratory use in research and industry. The DSC1 measures a voltage, computes a feedback signal according to the user selected control algorithm, and outputs a voltage. The product may only be used in accordance with the instructions described in this manual. -
Page 5: Specifications
Compact Digital Servo Controller Chapter 1: Introduction Technical Data 1.4.1 Specifications Operating Specifications System Bandwidth DC to 100 kHz Input to Output -180 Degree Frequency >58 kHz (60 kHz Typical) Nominal Input Sampling Resolution 16 Bit Nominal Output Resolution 12 Bit Maximum Input Voltage ±4 V Maximum Output Voltage... -
Page 6: Mechanical Drawings
Simplified Declaration of Conformity The full text of the EU declaration of conformity is available at the following internet address: https://Thorlabs.com/newgrouppage9.cfm?objectgroup_id=16794 FCC Designation Note: This equipment has been tested and found to comply with the limits for a Class A digital device, pursuant to part 15 of the FCC Rules. -
Page 7: Chapter 3 Installation
Although the DSC1 is unlikely to cause a ground loop in of itself, other instruments in a user’s lab may not have ground loop isolation and thus could be a source of ground loops. -
Page 8: Powering The Dsc1
Powering the DSC1 The DSC1 Digital Servo Controller requires 5 V power through the USB-C at up to 0.75 A peak current and 0.55 A in typical operation. Thorlabs offers two compatible power supplies: the CPS1 and DS5. In applications where noise sensitivity is less constrained or where runtimes of greater than 8 hours are required, the DS5 regulated power supply is recommended. -
Page 9: Touchscreen Operation In Ramp Mode
Compact Digital Servo Controller Chapter 4: Operation • The I (integral) control sets the integral gain coefficient. This may be a positive or negative value between and 10,000, notated in engineering notation. • The D (derivative) control sets the derivative gain coefficient. This may be a positive or negative value between 10 and 10,000, notated in engineering notation. -
Page 10: Touchscreen Operation In Peak Mode
Compact Digital Servo Controller Chapter 4: Operation 4.1.4 Touchscreen Operation in PEAK mode The PEAK mode implements an extremum seeking controller with user configurable modulation frequency, amplitude, and integration constant. Note that the modulation and demodulation is always active when the device is in PEAK mode;... -
Page 11: Launching The Software
Compact Digital Servo Controller Chapter 4: Operation This software allows for use of the device in the servo, peak, or ramp modes with control over all parameters and settings. The system response may be viewed as the input voltage, error signal, or both, either in the time domain or frequency domain representations. -
Page 12: Servo Software Tab
Compact Digital Servo Controller Chapter 4: Operation 4.2.2 Servo Software Tab The Servo tab allows a user to operate the device in servo mode with additional controls and displays beyond those provided by the embedded touchscreen user interface on the device itself. On this tab, either time or frequency domain representations of the process variable are available. -
Page 13: Ramp Software Tab
Compact Digital Servo Controller Chapter 4: Operation • Scans In Average: This numeric control determines the number of scans to be averaged. The minimum is 1 scan and the maximum is 100 scans. The up and down arrows on a keyboard increase and decrease the number of scans in the average. -
Page 14: Peak Software Tab
Compact Digital Servo Controller Chapter 4: Operation Figure 8 Software interface in Ramp mode. In addition to the controls available in Servo mode, the Ramp mode adds: • Amplitude Numeric: This value sets the scan amplitude in volts. • Offset Numeric: This value sets the scan offset in volts. •... -
Page 15: Saved Data
Compact Digital Servo Controller Chapter 4: Operation Figure 9 Software interface in Peak mode with the time-domain display. In addition to the controls available in Servo mode, the Peak mode adds: • Amplitude numeric: This value sets the modulation amplitude in volts. •... -
Page 16: Chapter 5 Theory Of Operation
Compact Digital Servo Controller Chapter 5: Theory of Operation Figure 10 Data in .csv format exported from the DSC1. Chapter 5 Theory of Operation PID Servo Control The PID circuit is often utilized as a control loop feedback controller and is very common in servo circuits. The purpose of a servo circuit is to hold the system at a predetermined value (set point) for prolonged periods of time. -
Page 17: Pid Theory For A Continuous Servo Controller
Compact Digital Servo Controller Chapter 5: Theory of Operation Please note that a PID circuit will not guarantee optimal control. Improper setting of the PID controls can cause the circuit to oscillate significantly and lead to instability in control. It is up to the user to properly adjust the PID parameters to ensure proper performance. -
Page 18: Data Format
5.3.1 Data Format The PID controller in the DSC1 receives a 16-bit ADC sample, which is an offset binary number, that can range from 0-65535. 0 maps linearly to a negative 4V input and 65535 represents a +4V input signal. -
Page 19: Approximating The Integral And The Derivative
5.3.3 Approximating the Integral and the Derivative The DSC1 approximates an integrator with an accumulator. ∫ ��[��] = �� [ �� ] + ∫ �� [ �� − 1 ] Consideration of the interval of integration, the timestep width, is wrapped into the integral gain coefficient ��... -
Page 20: Control Law In The Frequency Domain
Although the equation derived in the proceeding section informs the time-domain behavior of the discrete-time PID controller implemented in the DSC1, it says little about the frequency domain response of the controller. Instead we introduce the �� domain, which is analogous to the Laplace domain, but for discrete rather than continuous time. - Page 21 Compact Digital Servo Controller Chapter 5: Theory of Operation −1 ∫ ��(��) = ∫ ��(��) �� + ℎ��(��) −1 ∫ ��(��) − ∫ �� ( �� ) �� = ℎ��(��) ∫ �� ( �� ) (1 − �� ) = ��(��) ℎ...
- Page 22 The PID loop can lock to either a positive or negative slope by changing the sign of the P, I, and D gains. In the DSC1, the signs are locked together so changing one will change them all. Manual tuning of the gain settings is the simplest method for setting the PID controls. However, this procedure is done actively (the PID controller attached to the system and the PID loop enabled) and requires some amount of experience to achieve good results.
- Page 23 P . Gains are for various control circuits are then given in the chart above. Note that when using the Ziegler-Nichols tuning method with the DSC1, the integral term determined from the table should be multiplied by 2⋅10 to normalize to the sample rate.
- Page 24 Note that the peak may be positive or negative. To get started with the peak locking mode of operation for the DSC1, you may follow this procedure. 1. Make sure that there is a peak (or valley) of the signal you are locking to is within the control voltage range of the actuator, and that the peak position is relatively stable with time.
- Page 25 6. Set the modulation frequency to the desired frequency. On the touch screen this is affected through the M, modulation frequency parameter. The modulation frequency is 100 Hz times M. The best modulation frequency selection depends on the application. Thorlabs recommends values around 1 kHz for mechanical actuators. Higher frequencies may be used to electro-optic actuators.
- Page 26 Contact Thorlabs for more information. Waste treatment is your own responsibility. “End of life” units must be returned to Thorlabs or handed to a company specializing in waste recovery. Do not dispose of the unit in a litter bin or at a public waste disposal site. It is the user’s responsibility to delete all private data stored on the device prior to disposal.
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Page 27: Chapter 9 Thorlabs Worldwide Contacts
Compact Digital Servo Controller Chapter 9: Thorlabs Worldwide Contacts Chapter 9 Thorlabs Worldwide Contacts For technical support or sales inquiries, please visit us at for our most up-to-date www.thorlabs.com/contact contact information. Corporate Headquarters Product Manufacturer Thorlabs, Inc. Thorlabs, Inc. 43 Sparta Ave... - Page 28 www.thorlabs.com...
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