What is "Distributed IO" and what is "Remote IO"

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Thread Starter

Anonymous

Can someone explain the difference between a Distributed IO Product and a Remote IO Product.
And I am not talking about the Allen-Bradley Remote IO network here.
 
S
Distributed I/O is generally where you have multiple processors contolling different sections of an operation, and the processors share data with each other in order to coordinate the overall machine/process. Remote I/O is generally where you have a single processor controlling I/O that is physically located in different areas. These terms are often used loosely so one must make sure what the person actually wants when they refer to something as distributed I/O, althought when someone says Remote I/O you are usually safe to assume only one processor.

I hope this helps you understand the basic difference, althought many do not seem to.
 
A
hello,

A remote I/O simply means that the I/O card or I/O module is kept at a remote place or at a distance from the other cards like processors etc. An example is the TRIO system in ABB (or Taylor Mod 300) DCS. Here the I/O modules are connected to the processor by field bus cables.

While a Distributed I/O means that the I/O cards are connected on a bus and distributed geographically.

Remote I/Os can be distributed but this is not necessary.

It is possible that many remote I/Os have a chassis, slots, and modules etc. so a number of modules can be connected to one chassis in a remote place.

Distributed can be best visualized by seeing a module with a few I/Os and power supply say near a reactor, connected to another distributed module, near a pump some 100 meters away, and both connected to a PC 500 Meters away.

Hope this clarifies.

Anand
 
B
In the Schneider (Modicon) world...

Remote I/O is racks and modules that are directly connected by multiconductor cables to the rack that contains the PLC processor. By using multiconductor (parallel) cables, the data throughput is very high and secure. Data, configuration and diagnostic information are "automatically" available. Data does not have to "packaged" into a serial protocol for sending to the I/O.

Distributed I/O is racks and modulues that are connected by some communciations protocol over a communications cable. Modbus, Modbus Plus, Modbus TCP/IP, Profibus, Interbus-S, etc. This type of I/O often does not provide as much information back to the processor because all info, including diagnostics, must be "packaged" into the comms and sent/received.
 
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Pierre Desrochers

The Distributed system are what it says... the control is distributed, hence if the link was to fail, the I/O would still function. Of course, you would miss some Seppoints and other usefull things :)

When distributing a control system, one have to plan for such failures.

A remote I/O network is just a more technical way to bring an I/O closer to it's operation device. It saves on copper wire.
 
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