Which I/O Should I Use?
If you don’t already have I/O for your Raspberry Pi project, you should base your decision on the sensors and actuators you plan to use.
- Opto 22 G4 I/O has 1 point per module. Input modules are used to sense field signals. Each output module is individually fused and can switch up to 3 A.
-
Opto 22 SNAP I/O takes up less space with 4 points per module and costs less per point. 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.
For specifications and wiring instructions, see Opto 22’s form 2208, Digital I/O for Raspberry Pi Selection Guide
Note: If you already have Quad Pak or G1 I/O digital modules, the carrier board also supports the PB16HQ, PB4H, PB8H, and PB16H racks.
Pi-compatible G4 Products
G4 I/O Modules
G4 I/O modules have a built-in LED status indicator to display the point’s on/off status.
Note: 15 and 24 VDC logic modules are not supported.
| Model | Input | Output | Field Voltage | Special Features |
|---|---|---|---|---|
| G4IAC5 | x | 90–140 VAC/VDC | ||
| G4IAC5A | x | 180–280 VAC/VDC | ||
| G4IAC5L | x | 90–140 VAC/VDC | Low input resistance | |
| G4IAC5MA | x | 90–140 VAC/VDC | Diagnostic switch | |
| G4IDC5 | x | 10–32 VDC 12–32 VAC |
||
| G4IDC5D | x | 2.5–28 VDC | High speed | |
| G4IDC5G | x | 35–60 VDC/VAC | ||
| G4IDC5MA | x | 10–32 VDC 12–32 VAC |
Diagnostic switch | |
| G4SWIN | x | NA | Simulates input | |
| G4OAC5 | x | 12 VAC–140 VAC @ 3 A | ||
| G4OAC5A | x | 24 VAC–280 VAC @ 3 A | ||
| G4OAC5A5 | x | 24 VAC–280 VAC @ 3 A | Normally closed | |
| G4OAC5MA | x | 12 VAC–140 VAC @ 3 A | Diagnostic switch | |
| G4OAC5AMA | x | 24 VAC–280 VAC @ 3 A | Diagnostic switch | |
| G4ODC5 | x | 5–60 VDC @ 3 A | ||
| G4ODC5A | x | 5–200 VDC @ 3 A | ||
| G4ODC5MA | x | 5–60 VDC | Diagnostic switch | |
| G4SWOUT | x | NA | Simulates output |
G4 Mounting Racks
The G4PB16H and G4PB8H mounting racks are designed for G4 I/O modules and can accommodate up to 10 AWG wire. The logic supply is fused with a 1 A fuse.
| Model | Capacity |
|---|---|
| G4PB16H | holds 16 I/O modules |
| G4PB8H | holds 16 I/O modules |
G4 Power Supplies
Although it’s possible to power the rack and I/O modules from a Raspberry Pi, Opto 22 recommends powering from the rack’s power supply to ensure sufficient, consistent, and reliable power to the Pi and other attached hardware.
| Model | Input Voltage | Output Current |
|---|---|---|
| PBSA | 120 VAC input | 0.5 A |
| PBSB | 220 VAC input | 0.5 A |
| PBSC | 12/24 VDC input | 1.5 A |
Power Peripherals
If your Pi uses USB-powered peripherals (like hard drives or WiFi dongles), you’ll need a power supply that puts out more current:
- Connect a 5 V power supply rated 2.5 A to 5 A to the G4 rack’s power terminals.
- Replace the G4 rack’s standard 1 A fuse with the 5 A fuse (replacement part FUSE05B—10 pack) included with the Carrier Board.
Pi-compatible SNAP Products
SNAP I/O Modules
SNAP I/O modules have four points, and each point has an LED to indicate its status.
| Model | Input | Output | Field Voltage | Special Features |
|---|---|---|---|---|
| SNAP-IAC5 | x | 90–140 VAC/VDC | ||
| SNAP-IAC5A | x | 180–280 VAC/VDC | ||
| SNAP-IAC5MA | x | 120 VAC/VDC | 4 isolated channels, manual/auto switches | |
| SNAP-IDC5 | x | 24 VAC/VDC | ||
| SNAP-IDC5D | x | 5 VDC | ||
| SNAP-IDC5G | x | 48 VAC/VDC | ||
| SNAP-IDC5-HT | x | 24 VAC/VDC | Leakage-tolerant | |
| SNAP-IDC5MA | x | 24 VAC/VDC | 4 isolated channels, manual/auto switches | |
| SNAP-IDC5-SW | x | 15 VDC | Dry contact, normally open | |
| SNAP-IDC5-SW-NC | x | 15 VDC | Dry contact, normally closed | |
| SNAP-OAC5 | x | 12–250 VAC | ||
| SNAP-OAC5-I | x | 12–250 VAC | 4 isolated channels | |
| SNAP-OAC5MA | x | 12–250 VAC | 4 isolated channels, manual/auto switches | |
| SNAP-ODC5SRC | x | 5–60 VDC | Load sourcing | |
| SNAP-ODC5SNK | x | 5–60 VDC | Load sinking | |
| SNAP-ODC5ASNK | x | 5–200 VDC | Load sinking | |
| SNAP-ODC5MA | x | 5–60 VDC | 4 isolated channels, manual/auto switches | |
| SNAP-ODC5-I | x | 5–60 VDC | 4 isolated channels | |
| SNAP-ODC5A-I | x | 5–200 VDC | 4 isolated channels | |
| SNAP-OMR6-C | x | 5–30 VDC 0–250 VAC |
Mechanical Power Relay, Form C | |
| SNAP-OMR6T-C | x | 5–30 VDC 0–250 VAC |
Mechanical Power Relay, Form C, with integrated transient suppression |
SNAP Mounting Rack
If you’ve decided to use SNAP I/O modules in your Pi project, the Carrier Board works with the SNAP-D4M mounting rack. The SNAP-D4M holds 4 SNAP I/O modules (a total of 16 points).
Note: The SNAP-DM4 mounting rack has a 1 A fuse. If you’re using peripherals, you’ll need to replace it with a 4 A fuse. For convenience, one of these is included with the Digital I/O Carrier Board for Raspberry Pi.
Power Supplies for SNAP
For a SNAP system for Raspberry Pi, you’ll need a 5 V power supply connected to the SNAP-D4M rack’s power terminals. For more information, see Opto 22 form 2208, Digital I/O for Raspberry Pi Selection Guide.