Industrial I/O devices have become a much-needed compulsion in the world of automation and form the nervous system of modern machines. Reliable and instant remote monitoring and control of equipment, control-systems, DBs, etc. have always been the key goals of all industrial plants. Since the inception of computers or more specifically PLC (programmable logic controllers), there have been many protocols and gateways that have allowed remote operation in one form or another.
A few examples that are very much established in the industry include:
1. Host-resident I/O boards
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.
2. RS-232 Ports
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.
3. RS-485/RS-422 Ports
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.
Since its inception and wide range acceptability, Ethernet has become the industrial world’s top contender for Remote I/Os and associated operations. They offer superior performance compared to other ports, like electrical insulation, elimination of ground loops, and long range connectivity. In addition, their benefits are backed by several strategic networking topologies that greatly reduce the initial & maintenance cost.
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:
- Remote space
- Physical conditions
- Bandwidth requirements
- Reliability & online time
- Time sensitivity
Keeping in check with these conditions, several breakthroughs have been made to further increase the reliability, speed and interoperability of Remote I/O systems.
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