Remote vs Distributed vs Ethernet io drops

[ahmed_atef97]

Please , i want a comparison between the three typed of drops & when to implement each solution

[Richard]

Remote I/O is highly deterministic where the response time can be calculated. Ideal for critical infrastructure.

Distributed I/O will get the message through but the response time cannot be accurately calculated. In fact responses from distributed I/O can be delayed if it on the same network as remote I/O as the latter is proritised, delaying DIO packets.

Both can be Ethernet I/O although distributed I/O can use other fieldbus connections..

[darren_clyde · Accepted solution]

Well, it really boils down to what do you want to do with the IO that is physically separated from the main PLC.  There are so many factors to select a path. You have to functionality, ease of use, cost, and now availability.  I think the confusion comes from how Schneider defines their hardware.

For Schneider in general they talk about "Remote IO" and use it synonymously with "Ethernet Remote IO (ERIO)" which is their time deterministic IO system.  This is used for mission-critical timing.  This may be where you have seen the "Ethernet IO drop"...same as "ERIO" in Schneider's world.  This is the M580 PLC family with x80 hardware.

For Schneider "distributed IO" is any other (what the industry, in general, would call) "remote IO" hardware. This is the confusion. This IO, is non-time deterministic IO that is physically separated from the main PLC connected by any serial or ethernet-based network. 

For "distributed IO". a plc would send a query to the IO system that is physically some distance away.   Simple application...read some inputs....figure out what to do and send some outputs whenever the processor gets to sending the update.  These are the M340, M200 series PLCs and would be any of the distributed IO systems you choose.  TM3 bus coupler, Advantys STB, Turck, Wago, Weidmuller, etc.