The legacy Optomux System is not recommended for new development. To update existing Optomux Systems, see Migrating to Newer Opto 22 Products.


The legacy Optomux System, released in 1982, was the first intelligent, serially addressable I/O system, using a simple open ASCII protocol.

The Optomux protocol soon became an industry standard for the distributed intelligent I/O market.

Optomux allowed thousands of points of I/O to be distributed anywhere along a mile-long serial communications link. Processor-intensive tasks, such as counting and latching, were off-loaded to the individual I/O racks. This advance made system performance independent of the number of I/O points.

Need I/O for your Optomux System?

If you’re replacing or adding I/O modules, your rack determines the modules you need. 

Need to replace Optomux brains?

  • Replace a digital B1 or analog B2 with a digital E1 or analog E2. Both are drop-in replacements. Visit the B1 and B2 migration path page to learn more.
  • E1s and E2s fit on the same racks and provide both serial and Ethernet networking. 

  • Replace a B3000 serial brain using Optomux with a B3000-B-OMUX