ACCES I/O Products supports critical infrastructure as defined by the US Department of Homeland Security and will be open during normal business hours 6 AM to 6 PM to serve our customers.
We are here to support you.

ROB-24 Relay Output Card


  • 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 and 4A on ROB-24H
  • 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
Model ROB-24 and ROB-24H are a 24-channel relay-output cards that can be controlled by digital inputs from ACCES IOD-Series digital I/O cards or other manufacturer's digital output cards. The card can be powered by either +5 VDC (ROB-24 or ROB-24H) or by 125 VAC (ROB-24-1 or ROB-24H-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 or ROB-24H-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 or ROB-24H-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 or ROB-24H, you can realize simple, inexpensive control of heaters, fans, lights, etc.

The ROB-24 may be interfaced to any port of any ACCES IOD-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 or ROB-24H-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


Programming ROB-24 is done by simple OUT statements. For example, if the card is to be controlled by an IOD-24E located at base address hex 310, BASIC statements would be used as follows:

10 OUT &H313,& H80

  • 'Sets the ports to use as outputs
20 OUT &H310,1
  • 'Activates port A, bit 0 (relay 0)
30 OUT &H311,16
  • 'Activates port B, bit 4 (relay 21)


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.

Available Reference Manuals

Available Software Downloads

Drivers and Downloads

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

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.

ModelPrice (USD)
Option 130.00
Option 240.00
Option 325.00
Option 520.00

Acquisition, Control, Communication: Engineering and Systems