SmoothStepper Ethernet Manual
Any machine tool is potentially dangerous. Computer controlled machines are potentially more dangerous than manual ones. Warp 9 Tech Design, Inc. does not accept responsibility for the performance of any machine or any damage or injury caused by its use. It is your responsibility to insure that you understand the implications of what you design and build and to comply with any legislation and codes of practice applicable to your country or state. If you are in any doubt you must seek guidance from a professionally qualified expert rather than risk injury to yourself or to others. This document is intended to give details about how to set-up the Ethernet SmoothStepper for the Mach3 system. It assumes that you are familiar with the contents of Artsoft’s documentation for Mach3.
Contents
General Overview
What is the Ethernet SmoothStepper?
The Ethernet SmoothStepper (ESS) is a high-performance external motion controller for Mach3 and Mach4. Because it has a connector that conforms to the Parallel Port standard, it integrates seamlessly with most devices that the Parallel Port driver of Mach interfaces with. It accepts high-level commands from Mach and produces Step & Direction signals that are compatible with nearly all step & direction motor drivers (it also has a quadrature mode for high-end motor drivers, but those are not common). Because it is a dedicated hardware device, it is capable of producing pulses at very high frequencies and with extremely low jitter compared to the Parallel Port driver and microcontroller-based solutions. In addition, the SmoothStepper is able to run on any flavor of Windows, both 32‑bit and 64‑bit. Mach will run under 32-bit or 64-bit, but an external controller such as the SmoothStepper is needed for 64-bit editions.
How does it connect in my system?
The computer connects to the ESS via a standard inexpensive Ethernet cable. The cable may be shielded or unshielded. An advantage of Ethernet compared to USB is that the cable length may be as long as 100 meters (328 feet). The maximum length for a USB cable is 5 meters, and that is pushing it in a noisy environment. Another advantage is that Ethernet uses transformers for coupling the data signals, which galvanically isolates the computer from the downstream electronics. (http://en.wikipedia.org/wiki/Galvanic_isolation) The ESS connects to the rest of your equipment via its three “parallel port” connectors. Since the ESS emulates parallel ports, Mach’s documentation for the Parallel Port Driver of Mach applies to the ESS as well.
The ESS is intended to connect to your equipment via a “parallel port breakout board”, sometimes called a “BOB”. This is a board that has one or more connectors that have a parallel port interface. Typically it is a 26-pin header that is identical to the connector on the ESS, or a DB25 just like the parallel port of a computer. This connection is usually made via a ribbon cable. An inexpensive alternative to a breakout board is to connect a ribbon cable to the ESS that has a 26-pin header at one end, and no connector at the other. Simply connect the wires of the ribbon cable to each component in your system. This method isn’t encouraged because you can’t easily swap things out when something is wrong. Breakout boards are very inexpensive and worth the money invested. Voltages are limited to a maximum of 5V when interfacing directly with the ESS, so this is a limitation that is easily overcome with a breakout board.
Can the ESS drive my motors directly?
The ESS is not a high-power device. Its drivers are strong, but not nearly strong enough to drive a motor. Its drivers must drive a “motor driver”, which is a device that accepts a lowlevel input and essentially amplifies it so that the motor can turn with force. What are Opto-Isolators and Ground Loops? An opto-isolator (often called “opto-isolator” or simply “opto”) is a device that has an LED inside that emits light. You don’t see the light because it is buried inside of the package it is in. A photo diode or transistor receives the light and allows electrical current to flow in proportion to the light. Thus no electrical current flows from one side of the opto to the other. Motor drivers often have opto-isolators in them to block current flow from the controller (ESS) to the high-current motor driver. There are other types of isolators, but the most common is an optical isolator because of its low cost. Isolation can also be achieved through capacitance, inductance (transformers), and RF (Radio Frequency). The ESS relies on the breakout board for isolation, though the ESS isolates the PC and user by virtue of the transformers in its Ethernet jack.
A ground loop is an unwanted current that flows from one circuit to another that are supposed to be at the same potential (voltage). If you have “ground” in one circuit, “ground” in another circuit might not be at the same voltage. If you hook a voltmeter between the two you would measure a voltage if the two were not the same. Having a different voltage at each end of a wire that connects the two grounds will result in a current flow, and that is undesirable. An electrical isolator blocks these currents because information is transferred from one circuit to the other without electrons (light or electromagnetic fields). The ESS has drivers that are capable of driving opto-isolators directly. This permits it to be used without a breakout board, or with a simple breakout board that connects the ESS’s I/O signals to screw terminals without going through any buffer ICs.
Which Breakout Board Should I Use?
Arturo Duncan of CNC4PC.com is asked this question quite often. His answer is that choosing a breakout board is much like choosing an automobile. Do you want a 4-cylinder car that gets good gas mileage? Or a pickup truck or SUV for hauling things? Does it need a trailer hitch? Do you want 4 doors? The same applies to CNC. Do you need to drive a spindle motor? Do you need relays for vacuum pumps or coolant pumps? Do you need opto-isolation? You probably don’t need isolators on the step & direction signals if they are driving motor drivers that have isolators on those lines already. The best way to approach this is to make a list of all of the signals that you need to control. If you ask someone which breakout board you should use and you don’t have this list, you’re probably going to get the automobile analogy for an answer. The Geckodrive G540 is a popular motor driver. This motor driver has a breakout board built into it. With the proper ribbon cable the ESS will connect directly to it without the need of any other breakout board.
Detailed Hardware Installation
| Ports 1, 2, and 3 | Parallel Port connectors. These connectors are standard 26-pin low-profile male headers. If a ribbon cable is connected that has a DB25 on the other end, the DB25 will have the pinout of the Parallel Port of a PC. |
| External 5V Input | Power input for the board. This supply must be a regulated supply
with a tolerance of ± 10% (± 5% is preferable). |
| Pin 26 5V Jumper for each port | Pin 26 of each header may be connected to the 5V power rail
of the ESS board. Some breakout boards also have this feature, which enables one of the two boards to supply power to the other. This is a simple connection without any electronics involved. Multiple breakout boards with their own power supplies may be connected to the ESS. Be careful not to bridge the supplies! |
| Ethernet Jack | Connect a standard Ethernet twisted pair cable (CAT5 or better) with RJ45 connectors to this jack. Connect the other end to the computer or a network switch. |
| Status LEDs | Displays connection and fault status. Defined elsewhere in this document. |
| Expansion Port | This connector will be used to connect to expansion boards that provide additional I/O. High-speed I/O will need to be on the main Port 1, 2, or 3 pins. The Expansion Port I/O will be suitable for slow-speed signals such as tool changers, relays, etc. |
| Config Jumper | This jumper is for programming the static IP address into the board. It may also be used for updating the bootloader in the microcontroller. For normal operation this jumper should be off. |
Power Supply
The ESS requires a 5V power supply. It draws about 300 mA (0.3 Amps) when its Ethernet port is active. Depending upon what is connected to the ESS, it might draw more. You will want to use at least a 500 mA supply, though it is highly recommended to use a 1-Amp supply since they don’t cost much more and the extra capacity will ensure that you won’t have problems. There are several types of supplies that can be used:
Wall Transformers are inexpensive and convenient if you have an AC receptacle available. They are available with a single style of AC prongs, or they are also available as plug-on attachments depending upon the country you are using it in. Most of these transformers are capable of running from 100-240V and 50 or 60 Hz. The barrel connector must be cut off in order to attach to the ESS’s screw terminals.
Table-Top Power Supplies are similar to wall transformers but they get their name because they sit on a table rather than in a wall receptacle. The advantage of a table-top supply is that you can cut the AC power cord’s plug and wire it in with the rest of your AC power. The barrel connector must be cut off in order to attach to the ESS’s screw terminals. The supply shown in the picture uses a standard computer style of power cord with a “C13” plug. (http://en.wikipedia.org/wiki/IEC_60320)
Open Frame Power Supplies are inexpensive, small, and lend themselves well to wiring the AC power without needing an AC receptacle. The board pictured here does not have a frame. Often they include an aluminum enclosure that only covers a portion of the PCB.
Din Rail Mount power supplies are handy if you have a DIN Rail in your cabinet.
Mounting Holes and Mechanical Drawing
The mounting hole that is in the upper right corner (next to the 5V power input) is grounded to the shield of the Ethernet jack. The other 3 mounting holes are not connected to anything. If you use a shielded Ethernet cable, the shield will be connected to the chassis if you use a metal standoff that connects to the chassis. It’s hard to say whether that is good or bad since it may or may not be connected to Earth ground on the PC side. It is best to ground a shielded cable at one end only. Here is a drawing showing the board dimensions, mounting hole locations, and the locations of the connectors.
