Reliable G4 I/O modules from Opto 22 just keep on working.  

Introduced in 1990, G4 I/O offered a more compact footprint than the earlier G1 and added an LED status indicator on the top of the module. Thousands of customers continue to rely on G4 discrete and analog I/O in their legacy Optomux and mistic systems. 

But G4 I/O isn’t just for legacy systems. Many new installations use it as well. Why?

G4 discrete I/O:

  • G4 discrete I/O can switch up to 3 A per channel.
  • Each module is individually fused. 
  • Wiring terminals on the rack are easy to use.

G4 analog I/O moduleG4 analog I/O:

  • G4 analog I/O provides complete electrical channel-to-channel isolation.
  • Isolation eliminates troublesome ground loop problems.
  • Wide variety of signal inputs include RTD, ICTD, voltage, current, thermocouple, and TPO.

Here are some ways G4 is used today.


Opto 22 G4 I/OAs industrial I/O for a Raspberry Pi.

Yes, you can sense and switch industrial signals with your Raspberry Pi. Use the Pi with G4 digital I/O for prototyping and in areas that do not require industrially hardened control equipment.

G4 I/O breakout boardFor  more robust SNAP PAC system sensing and switching.

Use a SNAP TEX breakout board to expand the capability of your SNAP high-density digital (HDD) I/O modules. The SNAP-UDC-HDB-G4 breakout board holds up to 32 G4 digital input or output modules to match the SNAP HDD input or output module you have. You get the 3 amp per channel ability of the G4 where you need it, mixed in with analog, digital, and serial modules on a compact SNAP PAC rack.

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E2 brain boardWith E1 and E2 brains in a legacy Optomux system.

E1 and E2 brains replace the obsolete B1 and B2 brains, work with G4 I/O, and provide communications over both Ethernet and serial networks. E1s and E2s are also designed for customers who need to upgrade Optomux systems to use Ethernet networking, while preserving existing I/O racks, modules, and field wiring.

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