Isolated SCMD Digital I/O Modules
Dataforth offers a broad line of digital input and output modules and accessories providing safe, reliable interfacing to industrial measurement and control applications. Installed near individual field loads, SCMD modules create a rugged protective isolation barrier, effective to 4kV, between the field and computer system.
Use of these modules can also reduce field wiring costs while establishing an economical, manageable approach for system expansion and repair.
The SCMD Series
SCMD miniature digital I/O modules are solid-state devices which send ON and OFF electrical signals to and from a computer.
- Input modules convert AC or DC voltages to DC logic signals and send them to the computer system
- Output modules work in the opposite direction, switching either AC or DC circuits on or off in response to logic-level voltage commands from the computer
SCMD modules are available in miniature versions of four basic types: AC input, DC input, AC output, and DC output.
SCMD-MIAC and -MIDC
SCMD-MOAC and -MODC
- Miniature input modules used for sensing ON and OFF AC or DC voltage levels in the ranges 10-60, 90-140, and 180-280VAC and 3.3-32 and 10-60VDC
- Low noise, fast switching, and other special features are available
SCMD-MORO and -MORC
- Miniature output modules accept 5VDC or 24VDC inputs and provide several different output ranges, including 12/24 to 140/280VAC and 0/3/5 to 50/60/200VDC
- Fast switching and other special options are available
- Miniature relay output modules used for switching AC and DC loads up to 125Vrms or 100VDC at maximum 30WDC or 62.5VA
- Proximity Switches
- Limit Switches
- Photoelectric Switches
- TTL Devices
Switch AC and DC loads in:
- Motor Starters
- Indicator Lamps
Frequently Asked Questions
What is the function of backpanels for signals?
Think of the backpanel as a bidirectional signal transfer device whose direction is determined by the module in a particular channel.
For an input module, the signal is transferred from the field-side screw terminals to the system/power supply-side screw terminals or to a signal access ribbon cable header or D-sub connector.
For an output module it is just the reverse, the signal is transferred from the system/power supply-side screw terminals or from a signal access ribbon cable header or D-sub connector to the field-side screw terminals.
Keywords/Phrases: backpanel, 5B backpanel, 7B backpanel, 8B backpanel, SCMD backpanel
Can Dataforth provide calibration reports for modules I purchased?
Yes we can provide calibration reports for the modules that you purchased.
You can either
a) visit https://www.dataforth.com/TestDataReport.aspx to search for Test Report Datasheets by Serial Number or
b) you can send us a list of model numbers and their serial numbers to firstname.lastname@example.org
In DC Digital Output Modules, does Dataforth have any with Iout > 3A?
Yes, Dataforth has the SCMD-MODC5ML which can switch up to 5A DC from an off-state voltage up to 50VDC.
The basic data sheet can be found in the Dataforth Full-Line Catalog under SCMD–MOAC/MODC Miniature Digital Output Modules and at www.dataforth.com at the upper left, under Explore our product offerings:, click on Signal Conditioning. Then click on Isolated Digital I/O Modules. In the top center of the next page, click on the Adobe Acrobat symbol to the right of SCMD–MOAC/MODC. At the right edge of the page in a text box labeled Datasheet, click on SCMD Specifications for detailed specifications of all Digital I/O Modules.
Keywords/Phrases: SCMD, SCMD–MOAC/MODC, SCMD-MODC, -MODC, Digital Output Modules, current, high, 3A, 5A
For SCMD-PB Digital I/O Backpanels, does Dataforth sell edge card connectors?
Dataforth does not sell the edge card connectors for the Digital I/O Backpanels, SCMD-PBxxxx. We do offer information about the part numbers and manufacturers of the connectors in the following lines.
Part Number Manufacturer
This information can also be found in the Dataforth Full-Line Catalog under SCMD Accessories Digital I/O Module Backpanels and at www.dataforth.com at the upper left under Explore our product offerings:, click on Signal Conditioning. Then click on Isolated Digital I/O Modules. In the top center of the next page, click on the Adobe Acrobat symbol to the right of Accessories.
Keywords/Phrases: SCMD, SCMD-PB, -PB
In the SCMD-MIDC5 manual, the maximum output voltage is 30V; if +Vcc is only 5V, how could output voltage be 30V and logic voltage 6V?
Nominal Logic Voltage (Vcc) is the module power supply voltage and is +5V. Maximum Logic Voltage is +6V. The output voltage is from an external power supply and there fore can be higher than the module Logic Voltage and is specified at a maximum of 30V.
Keywords/Phrases: SCMD, MIDC, MIDC5, SCMD-MIDC, SCMD-MIDC5
If the input range of my signal conditioner is -1V to +1V and the output range is 0 to 10V, does this mean that it ignores polarity?
A signal conditioner with these I/O ranges does not mean that the module ignores the polarity of your voltage input. The output of voltage input modules are scaled linearly, meaning an input of -1V would correspond to an output of 0V, an input of 0V would correspond to an output of 5V, an input of +1V would correspond to an output of 10V, and so on.
How do I convert an RMS voltage to its corresponding peak voltage?
To convert an RMS voltage to its corresponding peak voltage, you simply take the RMS voltage value and multiply it by the square root of 2, or roughly 1.414.
For example, 1500Vrms corresponds to a peak voltage of 1500 * 1.414 = 2121 Vp
Can the SCMD-MODC be used directly to drive loads such as solenoids? Or are these modules used to effectively step-up a low-level digital output, which can then get used to control a relay?
Yes, the SCMD-MODC modules can be used to directly drive loads such as solenoids. The maximum on state current for some SCMD-MODC models can be up to 5A.
How does the load resistance of a module affect the noise at the output?
Noise at the output of a module is independent of load resistance.
What is the difference between the SCMD-MORO5 and SCMD-MORO24?
The SCMD-MORO5 and the SCMD-MORO24 are functionally equivalent modules, however they have different input voltage and current specifications. Refer to the "SCMD Specifications" pdf on the "SCMD Series" page on our website to view the exact specifications of the modules.
How do I wire up an SCMD-MORO module?
Which terminal block you connect to on an SCMD backpanel will vary based on the model number of the board or what channel you are using. As a general rule for an SCMD-MORO module, the power supply is wired over pins 3 (+V) and 5 (Gnd). The input signal is wired over pins 4 (Sgnl) and 5 (Gnd). The output signal is over pins 1 and 2. Consult the schematic of your SCMD backpanel to determine which terminal blocks correspond to each pin.
What is the control current required for the relays in the SCMD-MORO?
The control current required for the relays is 2.2mA. You can find this information in the datasheet for the SCMD modules on our website: https://www.dataforth.com/catalog/pdf/SCMD-MXXX-specsheets.pdf
What is the minimum current required to switch the output for the SCMD-MODC?
The current required to switch the output for the SCMD-MODC is 27mA. You can find this information in the datasheet on our website: https://www.dataforth.com/catalog/pdf/SCMD-MXXX-specsheets.pdf
Can SCM5B modules be hot swapped?
Not just SCM5B modules, but any signal conditioning module series and MAQ20 I/O modules can be hot swapped. A minimal amount of signal settling time may result, but there will be no damage to the device.
Was this content helpful?