Distributed I/o

Is Any Difference Between Distributed I/o & Remote I/o ?

No standard definition on this. But from my perspective, the main difference is the distance. Generally remote I/O could reach further distance than distributed I/O, e.g : remote I/O could reach thousands of meters while distributed one only hundreds.

Imagine the concept of a typical Network.

Distributed IOs works on the same concept as a network. Informations are circulated only in an area by defination of say, maybe a master panel with six slave panels.

Remote IOs comes in mind as points that are out of the said network. For example, a few inputs from a Fire & Gas pump Panel from one area goes to the PLC inputs of an Engine Panel from another location.

Regards
Sherine T.

Hrm. I guess there is no real 'Standard' difference. I have always thought of remote I/O as a cable running to remote racks of I/O modules, and distributed I/O as a cable running to a bunch of small (1 or 2 point) I/O modules or to smart devices (Devicenet, Profibus, et al) that just hook right on to a control network.

To my mind, 'Remote I/O' concantenates the terminations from switches, sensors, starters, etc into two or more different locations, while 'Distributed' I/O has essentially a seperate location for every I/O device.

Datta..

I hope you doing ok...i have seen pics of heavy rainfall in bombay. I am surprised to see ur question posted on July31 (were u struck in office??).

I don't think this is definitive, but to me remote I/O indicates I/O that is an extension of a single PLC and treated the same as the "in rack" I/O. It, in effect, makes the I/O rack for a given PLC larger and allows more modules. Response time for the remote I/O is almost the same as the in rack I/O. An example would be the GE Series 1 or AutomationDirect 305, where a ribbon cable between the backplanes of two racks adds I/O capacity that is used by the main CPU exactly like the I/O card next to the CPU.

To me distributed I/O implies a communications link between a number of I/O units. The distributed I/O is periodically polled by a master. A classic example would be using a PC program to scan a number of remote I/O blocks like the A-B Flex I/O. The update time of the distributed I/O pints is longer, as it is limited by the throughput on the comm network.