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$451.00 (USA and Canada only)

Availability: In stock
Pulse & Direction Digital Outputs X2

Production Specification

The SNAP-SCM-ST2 pulse output module is a two-channel serial communication module that provides pulse and direction signals for stepper motor drives. Each channel is isolated from the logic side. The module can either output a constant frequency, or it can ramp from one frequency to another.

The SNAP-SCM-ST2 links up to two stepper motors which can then be controlled by a SNAP PAC controller running a PAC Control™ programming strategy. LED indicators are provided to indicate activity on each port.

The module snaps onto an Opto 22 SNAP PAC mounting rack. SNAP PAC racks accommodate up to 4, 8, 12, or 16 I/O modules, with a maximum of 8 serial modules (including SNAP-SCM-ST2) on any one rack. Because the SNAP-SCM-ST2 module is mounted on these standard racks with other SNAP I/O modules, you can use the combination of analog, digital, and serial modules required by your application at the location where they are needed.


Frequency Range

0.13–50,000 Hz

Pulse Width Range1

3.84 Sec to 10 µSec

Pulse Width Accuracy2

0–2 Hz, 2–30 Hz, 30–50,000 Hz
(see graphs on the next page)

Output Format

CMOS/TTL Compatible

Logic Supply Voltage

5.0 VDC

Logic Supply Current

200 mA

Compatible I/O Processors

SNAP PAC R-series controllers and EB-series brains with R9.1a or newer firmware

Duty Cycle

Fixed at 50%

Number of Ports per Module


Operating Temperature Range

-20–60 °C

Storage Temperature Range

-30–85 °C

Torque, hold-down screws Not to exceed 1 in-lb (0.11 N-m)
Torque, connector screws 5.22 in-lb (0.59 N-m)
Agency Approvals CE, RoHS, DFARS


30 months from date of manufacture

1Pulse Width is equal to one-half the period.

2To find the frequency error in Hz:
Frequency Error (+/-) = Desired Frequency - (1 ÷ (Pulse Width Resolution + (1 ÷ Desired Frequency))).

SNAP-SCM-ST2 Pulse Output Module Data Sheet

The SNAP-SCM-ST2 pulse output module is a two-channel serial communication module that provides pulse and direction signals for stepper motor drives.

SNAP Serial Communication Modules User's Guide

The SNAP-SCM-232, SNAP-SCM-485-422, SNAP-SCM-PROFI, SNAP-SCM-W2, SNAP-SCM-CAN2B, and SNAP-SCM-ST2 serial communication modules are designed for use with the SNAP PAC System and can also be used in standalone SNAP I/O units.

Each of these modules conveniently provides serial data at a remote Ethernet location.

  • The SNAP-SCM-232 and SNAP-SCM-485-422 typically interface with printers, scales, chart recorders, and barcode systems.
  • The SNAP-SCM-PROFI provides a standard electrical interface with PROFIBUS DP® networks.
  • The SNAP-SCM-CAN2B provides an interface to a Controller Area Network (CAN), so your SNAP PAC system can receive data from CANbus devices.
  • The SNAP-SCM-ST2 provides pulse and direction signals for stepper motor drives.
  • The SNAP-SCM-W2 complies with the Wiegand interface format and is used for access control applications.

Opto 22 RoHS 3 Statement of Compliance - Restriction of Hazardous Substances

This document is a statement of compliance with the EU Directive 2015/863/EU, Restriction of Hazardous Substances (RoHS 3). This document lists Opto 22 products that comply with the substance restrictions of the RoHS 3 directive.

CE Declaration: Low Voltage

This document is the Manufacturer's Declaration for the listed products as mentioned in the attachment - to which this confirmation refers - that they are in accordance with the mentioned European, international and/or national standards and regulations.

SNAP-SCM-ST2 Firmware

This file contains firmware for the SNAP-SCM-ST2 pulse output module. This firmware includes support for the ReadPulseFrequency command.

Video: Securing SNAP Module

A quick overview on securing a SNAP Module to a SNAP rack.

Video: Removing a SNAP Module

A quick overview on removing a SNAP module.

Accuracy vs Resolution

What's the difference between accuracy and resolution in analog I/O specifications? Try your own specs in the calculator.