1. Connecting the power supply

The MSST5-S accepts a DC supply voltage from 24 to 48VDC. The MSST10-S accepts a DC supply voltage from 24 to 80VDC.

Using the connector supplied and AWG 16 or 18 wire, connect to the power supply as in the diagram below.



Internal fuse: the MSST5-S and MSST10-S contain internal 10 amp fast acting fuses

External fuse (optional): if desired, we recommend:


Be careful not to reverse the wires. Reversing the connections may destroy the drive and void the warranty.


When a step motor decelerates, it converts the kinetic energy of the load into electrical power, much like a generator. Some of this power is consumed in the motor and some in the drive. In applications involving large loads running at high speeds, considerable energy is transferred to the power supply. Generally, simple, linear power supplies have large capacitors capable of absorbing this energy without damage. Switching power supplies usually shut down due to an over voltage condition. Excess energy is then transferred back to the drive and can damage it. To prevent this, the use of an RC-50 regen clamp is recommended as illustrated below.


2. Connecting the Motor

Never connect the motor to or disconnect it from the drive. Insulate unused motor leads separately, and then secure. Never connect motor leads to ground or to a power supply.

There are several options for connecting a motor to a drive.

Four lead motors can only be connected one way, as in the drawing below:


Six lead motors can be connected in series or center tap. When connected in series, motors pro­duce more torque at low speeds, but cannot run as fast as in the center tap configuration. In series operation, the motor should be operated at 30% less than the rated current to prevent overheat­ing. Wiring diagrams for both connection methods are shown below.


Note: NC = not connected

Eight lead motors can also be connected in two ways: series and parallel. As with six lead motors, series mode will provide more torque at low speeds and less torque at high speeds. When connected in series, the motor should be operated at 30% less than the rated current to prevent overheating. The wiring diagrams for eight lead motors are shown below.


3. Connecting to the PC using RS-232

Locate your computer within 6 feet of the stepping driver.

Your driver was shipped with a black adapter plug. It has a telephone style jack at one end and a larger 9 pin connector at the other. Plug the large end into the COM1 serial port of your PC.

Secure the adapter with the screws on the sides. If the COM1 port on your PC is already used by something else, you may use the COM2 port for the stepping driver. On some PCs, COM2 will have a 25 pin connector that does not fit the black adapter plug. If this is the case, and you must use COM2, you may have to purchase a 25 to 9 pin serial adapter at your local computer store.

Another choice other than COM serial port you can select is using USB port on your computer via a USB port to RS232 adapter available on market.

4. Connecting the inputs and outputs

The inputs and outputs are connected using pluggable, screw terminal connectors. The three inputs

(STEP, DIR, EN) are on the six position connector. The analog input and the digital output are on the five position connector along with 5VDC and a ground for analog connections.

4.1 Connecting Digital Inputs


4.2 STEP&DIR Digital Inputs

The S drives include two high speed inputs called STEP and DIR. They accept 5 volt single-ended or differential signals, up to 2 M Hz. EN is a 5 to 12 volt standard digital input that can be used for motor enable, alarm reset, or oscillator speed change.

All inputs are configured using the ST Configurator software.

STEP and DIR inputs can connect to an indexer, a master encoder or CNC hand wheel for following applications, or they can be used for connecting sensors, switches and other electronic devices. They can be used as the run/stop and direction inputs for velocity (oscillator) mode.


4.3 High Speed Input

PLCs do not commonly use 5 volt logic. Signal levels as high as 24 volts may be connected to the STEP and DIR inputs if external dropping resistors are added as shown below:

▪For 12 volt logic, add 820 ohm, 1/4 watt resistors

▪For 24 volt logic, use 2200 ohm, 1/4 watt resistors

WARNING: The maximum voltage that can be applied directly to a high speed input termi­nal is 5 volts. Never apply high voltage AC to an input terminal.


4.4 EN Digital Input

As mentioned above, the STEP and DIR inputs are configured for 5 volt logic. The EN input is designed for operation between 5 and 12 volts. Add 1500ohm to En for 24 volt operation.


4.5 Analog Inputs


The MSST5-S and MSST10-S have one 0 to 5 volt analog input that can be used by the drive for controlling the motor speed in velocity mode. This input can also be used to read a voltage using the SCL “IA” commands.


WARNING – The analog input must be used with care. It is not optically isolated and may operate improperly or could be damaged when system grounds are not compatible.

4.6 Connecting the Digital Output

The MSST5-S and MSST10-S drives include one digital output that can be used in one of five ways:

Brake: Control an electric brake relay, automatically releasing and engaging as the drive requires

Motion: indicates when the motor is moving

Fault: closes when a drive fault or alarm condition occurs, the red and green LEDs will flash an error code

Tach: produces pulses proportional to the distance traveled (and thereby a frequency that is proportional to motor speed).

General purpose: digital output controlled by the SCL SO, FO, IL and IH commands

The output has separate + and – terminals and can be used to sink or source current. Diagrams of each type of connection follow.

Do not connect the outputs to more than 24VDC.

The current through each output terminal must not exceed 10 mA.