A few examples that are very much established in the industry include:
These are boards that plug into a computer’s expansion slots and allow the transfer of data, e.g. PCI Express and PC/104+ cards.
The boards offer high performance levels, while keeping costs to a minimum however they can become complicated with increasing number of connections resulting in bundles of cables, loop-problems and life-expectancy.
The RS-232 gateway is an extremely popular mode of connection and is still used in industrial connections such as PLCs, Energy Meters, etc. They are widely available and have become standardized over the years, but their expansion capabilities are very much limited by a slow baud rate.
May be considered as a more developed version of the RS-232, these ports are moderately expandable but have a more limited range, and less readily available.
Ethernet offers great flexibility in the handling of protocols. Almost every industrial protocol such as MODBUS has a TCP (ethernet) implementation.
The Future of Remote I/O is highly constrained by factors such as:
Keeping in check with these conditions, several breakthroughs have been made to further increase the reliability, speed and interoperability of Remote I/O systems.