The Sciencetech MD100 is an external stepper motor controller with its own chassis and power supply. It is used to drive the motorized grating turret of Sciencetech's line of monochromators and it is also used by most Sciencetech motorized accessories such filter-wheels, the SS83 motorized slits, and flipping mirrors. Its standard computer interface is through RS-232 serial commands, although a USB to RS-232 adapter or GPIB to RS-232 adapter is available at additional cost. The MD100 is not used by Sciencetech's motorized choppers or high resolution model SS83-HR motorized slits which have their own special actuators and controllers. The controller includes a microprocessor with a set of programmed commands so that your processor is not burdened with actual pulse running of the motor. The controller allows the selection of two stepping modes: micro-stepping or half-stepping. In the micro-stepping mode very high scanning resolution is achievable, with 10μs per full step. Selection of the half-step mode allows faster scanning speeds. The MD100 features serial port control so that it can be interfaced with any computer. When purchased with a monochromator it has one or two end-travel switches for reference positions. The unit can be wired for all world voltage. It comes with an RS232 cable with DB25 connector, cable and monitor. Motors with 200 or 400 steps per revolution are available. A high torque motor with 200 steps per revolution is included in the MD200 motor drive system. Typical maximum scanning speeds are 150μsec/μstep and 500μsec/half-step. As an extra option a system that can reach 100μsec/μstep can be supplied. To calculate the maximum motor speed, multiply the time per step times the number of steps. For example this would yield 5 revolutions per second for the motor with 200 steps/revolution in half-step mode. Bi-Directional Control The MD100 can spin the stepper motor clockwise or counterclockwise and hence such commands can be given to it by the software. For example, the Sci-FilterWheel Active-X software has intelligent logic that allows it to change slot positions bi-directionally. If the filter-wheel is on Slot Position 3, the software would instruct the MD100 stepper motor controller to spin filter-wheel forward to Slot Position 4 or backwards to Slot Position 2. It would not move from Slot Position 3 to Slot Position 2 by going forward around all of the slot positions. However, there is still one small software flaw that needs to be fixed. Since Sci-Filterwheel software is used universally for all Sciencetech filter-wheels from the 4 slot model to the 8 slot model, it cannot apply this intelligent logic at the cross over point from the last slot to the first slot. For example, in a 4 slot filter-wheel, it would still go back 3 positions from Slot Position 4 to Slot Position 1 rather than going forward one position. This is a problem with the software, and not the capability of the MD100. Full Stepping and μstepping The MD100 supports both Full Stepping and μstepping (10 μsteps in a full step) of stepper motors. This is a software selectable feature as there are no dip switch settings required on the MD100 itself nor are there different versions of the MD100 for micro or full stepping. Compatibility with Prior Versions Please note that the MD100 has an internal ROM chip that interprets and executes the various ASCII commands that is sent to it from the SciSpec, SciLDA, or SciMono software residing on the computer. This MD100 internal ROM chip has changed versions over the years and hence may not be backward compatible. For example, a customer has reported that the 2006 Sci-Spec software cannot be used to control an MD100 manufactured in 1998 as its ROM chip is not compatible with the new software ASCII codes. The solution is to purchase a new MD100 with the latest software. Opto-Sensor Shut Off Control When used with Sciencetech Monochromators and Spectrographs, the MD100 can shut off the internal opto-sensor end switch during scanning to avoid IR light pollution inside the monochromator/spectrograph body. This is a new feature added in 2007. Sci-Spec, Sci-LDA, and Sci-Mono have been updated to include this feature. Technical Specifications

• Type of operation: Bipolar
• Stepping modes available: Full, Half, Micro (10 μsteps per full step)
• Number of phases: 2
• Maximum output current per phase: 400mA
• Maximum output voltage per phase: 40V
• Recommended motor phase inductance: 8mH to 40mH
• Input: 115Vac/230Vac, 0.5A/0.25A, 60/50Hz
• Dimensions: 8"x4"x2"
• Weight: 3lbs
• Fusing: 1A, 115V, 60Hz
• Voltage: 115, 230, 100, 240 V (internally configured)
• Motors: 11oz-in torque, 200 or 400 steps per revolution 22.2oz-in torque, 200 steps per revolution 44.4oz-in torque, 200 steps per revolution
• Steps Per Revolution: 200 ; 400
• Number of μsteps per step: 10 ; 10
• Number of half-steps per step: 2 ; 2
• Max. step rate in half-step (μsec/half-step starting): 700 ; 500
• Max. step rate in half-step (μsec/half-step running): 500 ; 400
• Max. step rate in μstep (μsec/μstep starting): 150 ; 140
• Max. step rate in μstep (μsec/μstep running): 140 ; 140
• Max. run vel. in half-step mode (rev/sec): 5 ; 3.1
• Max. run vel. in μstep mode (rev/sec): 3.5 ; 1.8
• For monochromator with 100 nm/rev.
• Max. scan rate in half-step mode (nm/sec): 500 ; 310
• Max. scan rate in μstep mode (nm/sec): 350 ; 180