Industrial I/O for your Rasperry Pi - Rack & I/O Selection Guide

Sense and switch industrial-level loads with your Pi.

Along with your Raspberry Pi and and the digital I/O Carrier Board, you'll need to select the input and output modules specific to your application.

This guide will help you select the ideal rack system (G4 or SNAP), rack size, and I/O modules.

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Here's what you'll need to complete your system:


Digital I/O Carrier Board for Raspberry Pi (OPTO-P1-40P)

The OPTO-P1-40P carrier board provides a GPIO interface between your Raspberry Pi and Opto 22 digital I/O modules on select mounting racks. Interface cable and Pi board mounting standoffs included.

Order from Opto 22 Order from Allied Order from Newark

Just plug the carrier board's interface cable into your Pi's 40-pin GPIO connector, and snap the board onto a compatible Opto 22 I/O mounting rack.

See the GPIO pinout diagrams.


Get a complete starter kit with everything you need to get started with digital I/O for your Raspberry Pi. All you need is your Raspberry Pi and a 5V 2A power supply.

We've bundled the most popular I/O and rack choices at a special low price: Just $129 plus shipping (a $215 value)

Order Your Starter Kit Today!

Click for more details, including what parts come with the starter kit.

I/O Mounting Racks—Choose one based on density and number of I/O points you need.

Choose G4 or SNAP I/O:

G4 I/O has 1 point per module. Each output module is individually fused and can switch up to 3 A.

  • G4PB8H - Holds 8 G4 I/O modules (8 points)
  • G4PB16H - Holds 16 G4 I/O modules (16 points)


SNAP I/O takes up less space with 4 points per module and costs less per point. (The image below shows a SNAP system with 16 points.) Most output modules can switch up to 0.75 A per point or a total of 3 A per module. SNAP-OMR6 modules can switch up to 6 A.

  • SNAP-D4M - Holds 4 SNAP I/O modules (16 points)


Note for customers who prefer to use Quad Pak or G1 I/O digital modules: the carrier board also supports the following racks: PB16HQ, PB4H, and PB16H.

I/O Modules—Choose I/O based on the sensors and actuators you will connect to.

G4 I/O modules (use with G4PB8H or G4PB16H racks)
SNAP I/O modules (use with SNAP-D4M rack)
For more details on compatible modules & racks, see Digital I/O for Raspberry Pi Selection Guide.

G4 Inputs (1 point each)

Sensor signal required Input module part #
90–140 VAC/VDC G4IAC5
180–280 VAC/VDC G4IAC5A
90–140 VAC/VDC, low input impedance G4IAC5L
90–140 VAC/VDC, with manual/auto switch G4IAC5MA
10–32 VDC G4IDC5
2.5–28 VDC G4IDC5D
35–60 VDC G4IDC5G
10–32 VDC, with manual/auto switch G4IDC5MA
Digital Input Switch (to simulate an input) G4SWIN

G4 Outputs (1 point each)

Actuator signal required Output module part #
12–140 VAC G4OAC5
24–280 VAC, normally open G4OAC5A
24–280 VAC, normally closed G4OAC5A5
12–140 VAC, with manual/auto switch G4OAC5MA
24–280 VAC, with manual/auto switch G4OAC5AMA
5–60 VDC G4ODC5
5–200 VDC G4ODC5A
5–60 VDC, with manual/auto switch G4ODC5MA
Digital Output Switch, 250 VAC/VDC (to simulate an output) G4SWOUT


SNAP Inputs (4 points each)

Sensor signal required Input module part #
90-140 VAC/VDC, isolated, with manual/auto switch  SNAP-IAC5MA
2.5-28 VDC, low-voltage input SNAP-IDC5D
15-32 VDC, leakage-tolerant SNAP-IDC5-HT
10-32 VDC/VAC, isolated, with manual/auto switch SNAP-IDC5MA
Contact status, normally open SNAP-IDC5-SW
Contact status, normally closed SNAP-IDC5-SW-NC


SNAP Outputs (4 points each)

Actuator signal required Output module part #
12-250 VAC SNAP-OAC5
12-250 VAC, isolated channels SNAP-OAC5-I
12-250 VAC, isolated, with manual/auto switch SNAP-OAC5MA
5-60 VDC, load sourcing SNAP-ODC5SRC
5-60 VDC, load sinking SNAP-ODC5SNK
5-200 VDC, load sinking SNAP-ODC5ASNK
5-60 VDC, isolated, with manual/auto switch SNAP-ODC5MA
5-60 VDC, isolated channels SNAP-ODC5-I
5-200 VDC, isolated channels SNAP-ODC5A-I
Mechanical Power Relay, Form C SNAP-OMR6-C
Mechanical Power Relay, Form C, with integrated transient suppression SNAP-OMR6T-C


G4 Power Supplies—Choose one based on your input voltage (powers rack and Pi)

Typical Raspberry Pi rated mini-USB power supplies will work perfectly for powering the Pi and the I/O. However, we also offer optional industrial power supplies:

Input voltage Output current Part number
120 VAC 0.5 A PBSA
220 VAC 0.5 A PBSB
12/24 VDC 1.5 A PBSC

Note on peripherals: If your Pi uses USB-powered peripherals (like hard drives, displays, or WiFi dongles), you’ll need a power supply that puts out more current than these. With these peripherals:

  • Connect a 5 V power supply rated 2.5 A to 5 A to the G4 rack power terminals.
  • Replace the G4 mounting rack’s standard 1 A fuse with a 5 A fuse (shipped with the Carrier Board).

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