ROB-24: 24 SPDT (DPDT optional), Form C Relays Board

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  • 24 SPDT, Form C Relays (DPDT optional)
  • Fully compatible with any ACCES digital I/O card (except for IOD-64)
  • 3A carry-current contact ratings on ROB-24
  • Screw terminals for #14 through #22 AWG wire
  • LED status indicators for each relay
  • Removable Screw Terminal Option
  • Designed, made, supported, and manufactured in the USA
Last updated on July 3, 2024, 1:03 pm

Call – $249.00

In Stock


Model ROB-24 is a 24-channel relay-output cards that can be controlled by digital inputs from ACCES IOD- and DIO-Series digital I/O cards or other manufacturer’s digital output cards. The card can be powered by either +5 VDC (ROB-24) or by 125 VAC (ROB-24-1). In the former case, we can also supply a seven-foot cable, CAB-MLX, that mates with standard molex connectors used in personal computer power distribution. For operation from AC-power inputs, the “-1” versions of these cards, screw terminals for the AC-power input and a power transformer are included. The cards also contain 24 LED’s, one associated with each relay. These illuminate when their associated relays actuate.

For remote (RS-485) control of relays, you can also connect a modified ROB-24 to our RDG-24.

Each relay provides normally-closed and normally-open contacts (SPDT). If you need dual Form C contacts (DPDT), you may specify ROB-24-2.

I/O connectors for 50-pin connections (from ACCES’ IOD-Series cards) and 37-pin connectors are provided. The latter provide means to use these relay cards with other manufacturer’s cards if they use 37-pin connections. Interconnection to the digital output card can be via ACCES’ model CAB50F-xx ribbon cable to ACCES’ I/O cards or via CAB37-xx ribbon cable to other I/O cards. The relays are actuated by a 5-volt logic signal applied to appropriate pins of either the 50-pin or the 37-pin connector. If the digital-output card to be used has an unbuffered output (e.g., direct output from a type 8255 Programmable Peripheral Interface chip), then specify ROB-24-3. (Note: When Option 3 is selected, the relays will be actuated when power is applied to the card.) Thus, by use of ROB-24, you can realize simple, inexpensive control of heaters, fans, lights, etc.

The ROB-24 may be interfaced to any port of any ACCES IOD- or DIO-Series card. Normally, digital inputs are pulled down to ground through 680 ohm resistors. However, if you prefer that they be pulled up to +5VDC, you can specify ROB-24-5. You can have multiple options in the card. For example, if you need AC-powered capability, DPDT relay output connections, and signals will come from an unbuffered digital output card, then the model number becomes: ROB-24-1-2-3

We’re sorry to report that due to the 4A relay no longer being available the ROB-24H “High Current” model is no longer available for sale.


Two connectors are provided for control inputs; one in 50-pin format and one in 37-pin format. For 50-pin connectors, the mating connector is AMP 1-499776-0 or equivalent. For 37-pin connectors, the mating connector is an AMP 747304-1 or equivalent.




Drivers and Downloads

Full list of available Downloads: Software Packages, Drivers, Manuals, and other documents

Information about our Free Software packages:

ACCES is proud to provide a full suite of software support with every Data Acquisition product. We are committed to supporting the most popular operating systems and platforms for our customers. Currently we are actively supporting XP -> 10, both 32 & 64 bit, including “Server 2008,” “Embedded,” and “Compact” flavors for all plug-and-play products including PCI, PCI Express, USB, and more. Many products continue to ship with support for additional operating systems such as DOS, Windows 95, 98, Me, NT4, and 2000.


Among the software we deliver with our products are sample programs in a wide variety of programming languages. These samples are used to demonstrate the software interfaces to our products — and many can be used as-is in your production environments, or to test functionality of the devices out-of-the-box. We’re currently actively supporting sample programs in Microsoft Visual C#, Visual Basic, Delphi, and Visual C/C++, with many devices including samples in Borland C/C++ 3.1 for DOS. Additionally we provide National Instruments LabVIEW compatible DLLs and many demonstration VIs for our devices.


Drivers for various operating systems are also provided, including active support for Windows XP -> 10 — all in both 32-bit and 64-bit flavors, and including consumer, server, and embedded varieties — as well as the 2.6 and newer Linux kernels and recent OSX / macOS versions. Many products continue to ship with driver support for Windows 95, 98, Me, NT4, and Windows 2000, but support for these operating systems is considered deprecated.

Setup Programs and Utilites

Our Data Acquisition devices also include a graphical setup utility that walks you through the process of configuring any option jumpers or switches on the device, as well as explaining a little about the various connectors present.

Many devices also include utility programs – little tools to make your use of the device easier, such as EWriter, a program that allows you to read and write data in the user-accessible EEPROM locations on all our USB data acquisitition products; or WinRISC, a “Really Incredibly Simple Communications” terminal program that lets you get started instantly with serial devices.

“Register Level” Documentation

Besides all this software in all these languages and operating systems ACCES has a policy of open and transparent development: none of our lowest-level “register” interfaces are hidden from you — we document every register in every bus card, every command in every serial board, and every usb control transfer in every USB Data Acquisition board. These lowest-level interfaces allow you to develop for our products in ANY operating system or language, regardless of our actively supporting it or having a driver for it. We have customers actively developing in ADA, Android, Python, Java, MATLAB, Solaris, and more, just by referring to our complete low-level interface documentation! And we provide the full source code to all of our drivers, regardless of operating system, to give you an even bigger head start in your own development tasks.

No Fees or Royalties

All of this software is provided at no additional charge, and is licensed under any of a variety of flexible — and royalty free — options. Check out our software license explanation if you’d like more information.

Custom Software

ACCES also offers Custom Software Services for our products. Our prices are unbelievably low, often as inexpensive as free! If you need something tweaked to support your needs, or an entire enterprise application developed from scratch, it is definitely worth your time to inquire with us, first.

Further information about available ACCES Software:

Redistributing Windows Drivers
A list of ACCES drivers and the files that compose them under different versions of Windows, so you can easily redistribute ACCES cards and drivers.


  • Quantity and Type: 24 ea., SPDT, Form C. (DPDT optional.)
  • Contact Material: Gold overlay silver.
  • Max. Switched Current: 2A DC, 1.25A AC.
  • Max. Carry Current: ROB-24: 2A AC or DC; [ROB-24H: 4A AC or DC]
  • Max. Switched Voltage: 150 VDC or 220 VAC.
  • Max. Switched Power: 30 W / 60 VA on ROB-24  [360 VA on ROB-24H]. (Note: Good safety practice should be followed if AC voltages are to be switched at the relays.)
  • Actuate Time: ROB-24: 8 mSec; [ROB-24H: 20mSec] (including bounce).
  • Release Time: ROB-24: 8 mSec (including bounce); [ROB-24H: 10 mSec] (including bounce).
  • Mechanical Life Expectancy: 20 million operations minimum.


  • Operating temperature Range: 0o to 50oC.
  • Storage Temperature Range: -30o to +105oC.
  • Humidity: 45 to 85% RH, non-condensing.

Power Consumption (all relays ON)

  • 5 VDCPower: ROB-24: 2A, [ROB-24H: 4A] max.
  • 115 VACPower: ROB-24: 310mA, [ROB-24H: 390 mA] max.


  • Card Dimensions: 16″ long x 4.75″ wide x 2″ high (407mm x 121mm x 51mm)
  • Weight: 2.25 lbs.(1kg) max. (for Model ROB-24-1-2).
  • Screw Terminal Wire Spacing: 0.200″ (5 mm).
  • Screw Terminal Wire Sizes: 12 to 22 AWG.

We’re sorry to report that due to the 4A relay no longer being available the ROB-24H “High Current” model is no longer available for sale.

ModelDescriptionPrice (USD)
ROB-24H - discontinued

High-Current 24 Form C Relay Output Board


24 Form C Relay Output Card

Model Options (call for pricing)
-1 or -S01 Powered by 125 VAC power
-2 or -S02 Dual Form C contacts (DPDT