SNAP-SCM-ST2 Module
SNAP-SCM-ST2 PULSE OUTPUT
>>>
+Pulse
+Direction
+5 v
0 v
+5 v
0 v
MODULE
Features
Suited for pulse/direction applications with a frequency
range of 0.13–50,000 Hz
Dual outputs
Software configurable
DESCRIPTION
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 be
controlled by a SNAP PAC controller running a PAC Control™ 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.
SNAP racks have a retention rail locking system. Use two 4-40 by
½-inch standard machine screws to hold each module securely in
position on the SNAP rack.
NOTE: SNAP-SCM-ST2 modules require a SNAP PAC EB-series brain or
ies
controller with firmware R9.1a or newer. These modules do not
R-ser
work with SNAP PAC SB-series brains nor with legacy brains or controllers.
DATA SHEET
Form 1944-200318
PAGE 1
Commands Supported
The SNAP-SCM-ST2 module supports the following pulse output
commands in PAC Control:
SetPulseFrequency outputs a set frequency until instructed
to do otherwise.
SetPulseSequence ramps from one frequency to another.
ReadPulseFrequency returns a string representing a channel’s
current frequency. This command requires SNAP-SCM-ST2 module
firmware version R1.0d or newer.
These pulse output commands
the Transmit/Receive String command.
“Using the SNAP-SCM-ST2 Module Commands” in the SNAP Serial
Communication Module User’s Guide (form 1191).
are entered in PAC Control using
For more information, see
How the SNAP-SCM-ST2 Outputs Data
The SNAP-SCM-ST2 outputs a specified frequency based on the
command received, as shown here.
The Direction pin can be either +5 VDC or 0 VDC, as determined by
the parameters of the command executed. See “Using the SNAPSCM-ST2 Module Commands” in the SNAP Serial Communication
Module User’s Guide (form 1191).
Part Numbers
Part Description
SNAP-SCM-ST2 SNAP 2-Channel Pulse Output Module
© 2011–2017 Opto 22. All rights reserved . Dimensions and specifications are subject to change. Brand or product names used herein are trademarks or registered trademarks of their respective companies or organizations.
SPECIFICATIONS
Frequency Range 0.13–50,000 Hz
Pulse Width Range
Pulse Width Resolution 0–2 Hz, 2–30 Hz, 30–50,000 Hz (See resolution graphs on page 3)
Output Frequency Accuracy
Output Format CMOS/TTL Compatible
Logic Supply Voltage 5.0 VDC
Logic Supply Current 200 mA
Compatible I/O Processors
Duty Cycle Fixed at 50%
Number of Ports per Module 2
Operating Temperature Range -20–60 °C
Storage Temperature Range -30–85 °C
Torque, hold-down screws 4 in-lb (0.45 N-m)
Torque, connector screws 5.26 in-lb (0.6 N-m)
Agency approvals CE, RoHS, DFARS
Warranty 30 months from date of manufacture
1
Pulse Width is equal to one-half the period.
1
3.84 Sec to 10 µSec
To calculate error (in Hz) for the desired frequency, use this equation
and the resolution graphs on page 3the next page:
Frequency Error (+/-) = Desired Frequency - (1 ÷
(Pulse Width Resolution + (1 ÷ Desired Frequency)))
SNAP PAC R-series controllers and EB-series brains with R9.1a or
newer firmware
DATA SHEET
Form 1944-200318
PAGE 2
Pin Assignments
Pin Port Use Description
1
2 Ground Isolated from logic side
3 Direction
4 Ground Isolated from logic side
5
6 Ground Isolated from logic side
7 Direction
8 Ground Isolated from logic side
Pulse Frequency output
A
Pulse Frequency output
B
+5 VDC when asserted
0 VDC when deasserted
+5 VDC when asserted
0 VDC when deasserted
LED Indicators
LED Description
1 Blinks when outputting pulses on channel 1
2 Positive/Negative direction indicator on channel 1
3 Blinks when outputting pulses on channel 2
4 Positive/Negative direction indicator on channel 2
See diagram on page 4 for location of pin 1.
© 2011–2017 Opto 22. All rights reserved. Dimen sions and specifications are subject to change. Brand or product names used herein are trademarks or registered trademarks of their respective companies or organizations.
3.50E-05
3.00E-05
2.50E-05
2.00E-05
1.50E-05
1.00E-05
5.00E-06
0.00E+00
0 0.5 1 1.5 2 2.5
Frequency (Hz)
Pulse Width Resolution +/- (s)
Pulse Width Resolution for Frequencies from 0–2 Hz
Equation
3.871×10
-6
Frequency
0.993
Resolution=
2.00E-06
1.80E-06
1.60E-06
1.40E-06
1.20E-06
1.00E-06
8.00E-07
0.00E+00
0 5 10 15 20 25
Frequency (Hz)
Pulse Width Resolution +/- (s)
6.00E-07
4.00E-07
2.00E-07
30 35
Pulse Width Resolution for Frequencies from 2–30 Hz
Equation
3.795×10
-6
Frequency
0.993
Resolution=
1.40E-07
1.20E-07
1.00E-07
8.00E-08
6.00E-08
4.00E-08
2.00E-08
0.00E+00
0 100 200 300 400 50,000
Frequency (Hz)
Pulse Width Resolution +/- (s)
500 533.2
Pulse Width Resolution for Frequencies from 30–50,000 Hz
Transition Points
Frequency Resolution +/- (s)
533.20 7.15430×10
-9
266.60 1.43086×10
-8
177.73 2.14629×10
-8
133.30 2.86172×10
-8
106.64 3.57715×10
-8
88.87 4.29258×10
-8
76.17 5.00801×10
-8
66.65 5.72344×10
-8
59.24 6.43887×10
-8
53.32 7.15430×10
-8
48.47 7.86973×10
-8
44.43 8.58516×10
-8
41.02 9.30060×10
-8
38.09 1.00160×10
-7
35.55 1.07315×10
-7
33.33 1.14469×10
-7
31.36 1.21623×10
-7
29.62 1.28777×10
-7
DATA SHEET
Form 1944-200318
PAGE 3
© 2011–2017 Opto 22. All rights reserved . Dimensions and specifications are subject to change. Brand or product names used herein are trademarks or registered trademarks of their respective companies or organizations.
DIMENSIONS
Pin 1
SNAP-SCM-ST2 Pulse Output Module
DATA SHEET
Form 1944-200318
PAGE 4
© 2011–2017 Opto 22. All rights reserved. Dimen sions and specifications are subject to change. Brand or product names used herein are trademarks or registered trademarks of their respective companies or organizations.
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© 2001–2020 Opto 22. All rights reserved. Dimensions and specifications are subject to change. Brand or product names used herein are trademarks or registered trademarks of their respective companies or organizations.
Form 1335-200129
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