SD4DX Series of USB Controllers
SD4DX USB with screw terminal connectors
The SD4DX series of USB boards are designed to simultaneously operate up to four external step-and-direction driver boards (such as those produced by Applied Motion and Gecko1), allowing for easy control of up to four stepper motors. They also support "daisy-chaining" to any of our controller boards, giving you the ability to increase the number of motors which may controlled through use of one serial line.
When configured with the SD4DPotRouter firmware, the SD4DX series of boards permit independent control of the four motors. In addition to full serial control of each motor, the board also supports use of a user-supplied potentiometer to set target rates, combined with simple switch closures to control motor slews (thus allowing for simplified control of the motors without use of a computer). The product includes full support of separate limit switches to protect each direction of travel for each motor.
Similarly, these boards may be configured to operate in an NC (numerically controlled) process environment, through use of the SD4DNCRouter firmware option. This firmware tightly links the four motors together, providing for easy "exact straight line" and simplified arc/circle drawing. More information about the SD4DNCRouter firmware is available here.
The several different models of the SD4D series reflect differing customer requests, as well as general product evolution.
The retired SD4D was the original board in the series. It was not ROHS compliant, and strictly used 0-5 volt TTL outputs (which can handle at most 5 mA of drive current each) for its step-and-direction pulses. All of the later boards include a higher current transistor drive output, which can directly handle the common opto-isolator drive current as required for many step-and-direction boards (such as many in the Gecko product line).
The SD4DG was the first ROHS compliant product to add the transistor drive output. It also changed the USB configuration such that the USB chip was powered off of the USB system, as opposed to being powered off of the board power supply. This allowed the host computer to recognize the board's presence before it is powered, and it prevents loss of the virtual COM port if the board loses power.
The SD4DEI went a few steps further. It added a set of 1K pullup resistors on the step-and-direction output lines, so that they can be treated both as high-current transistor drivers (short-to-ground), and as simple TTL outputs. Additionally, it added digital isolation between the USB system and the rest of the board. This means that there is no longer a danger of there being a ground loop between your power supply used to power the board, and the computer's ground. It also adds ESD protection to all of the TTL I/O lines -- it is thus more protected against static shocks coming in on those lines.
The SD4DEU was almost identical to the SD4DEI. It's single change was to replace the digital isolation circuitry with the option of powering the board off of the USB bus. In this configuration, you no longer needed a separate power supply in order to make use of the board!
The SD4DX series is the upgrade to the SD4D product line which includes features from the SD4DEI, SD4DEU and the SD4DP products. The SD4DX supports firmware enhancements that include user flash memory, greatly improved motion control when operating using the NC firmware, optional dual-DAC 0 to 5 volt outputs, as well as user-controlled 'memorization' of firmware settings.
The SD4DX has the following key capabilities when using the SD4DPotRouter firmware:
- USB communications with a host computer may be used to control the board.
- Alternatively, TTL-Serial communications may be used to control the board using some external microprocessor, such as a Parallax Basic Stamp TM.
- Up to four step-and-direction stepper motor driver boards may be independently controlled at one time.
- Limit switches may be used to automatically request motion stop of any motor in either direction.
- Rates of 1 to 36,864 microsteps per second are normally supported.
- Step rates are changed by linearly ramping the rates; the rate of change is independently programmed for each motor, and can be from 1 to 38,462 steps per second per second on the older firmwares, and is effectively unlimited on the SD4DX product.
- Motor coordinates are maintained as 32 bit signed values, and thus have a range of –2,147,483,647 through +2,147,483,647.
- Both GoTo and Slew actions are fully supported.
- Separate 'backlash' adjustments are available for each motor.
- A TTL "busy" signal is available, which can be used to see if the motors are still moving. Note that this information is also available from the serial communications subsystem.
- Simple control of the motors may be done by switch closure: i.e., each motor can be told to slew left or right, or to stop by simply grounding some input lines. Similarly, the rate of motion can be controlled via stepping through a standard set of rates via grounding another input.
- Complete control of the motors, including total monitoring of current conditions, is available through the 2400 to 19,200 baud serial connection (by default, this is shipped configured for 9600 baud; other rates may be requested at the time of ordering the product).
- An additional mode is available which allows an external computer to directly generate step sequences on the motor control lines. Up to 38,864 steps per second may be requested.
- 6 spare generic TTL I/O lines are available for input and output as needed by your application.
- An additional 8 TTL I/O lines can be reassigned from their default behavior of providing for manual slew operations to use as generic TTL I/O signals.
- Runs off of a single user-provided 6.5 to 15 volt or 5 volt DC power supply.
- The SD4DX boards can be optionally configured to strictly operate off of the USB power.
- Theoretically, an unlimited number of boards can be controlled via one serial line, if the SerRoute product is used.
- The SD4DX adds options for a dual-5 volt dac or an extra 2 generic digital I/O ports,
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We accept American Express, MasterCard, Visa and Discover for orders from the USA. For international orders, we require wire transfers.
1 Note that additional external signal buffering may be needed in order for the board to operate some step-and-direction controllers, such as the Gecko products. Use of the SD4DG is recommended for such controllers.