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I need a system with fast scanning of 10 nos. 12 bit analog inputs. My hardware is configured as V570 + EX-DI16A3-TO16 + IO-DI16A3-TO16 + IO-DI16A3-TO16 + IO-DI16A3-TO16 + IO-AI4AO2 + IO-ATC8.

My question is " will changing the configuration to V570 + EX-DI16A3-TO16 + IO-AI4AO2 + IO-ATC8+ IO-DI16A3-TO16 + IO-DI16A3-TO16 + IO-DI16A3-TO16, improve the scanning ".

Thanks & regards


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  • MVP 2014

Hi Ron,

Since no one has offered an answer as yet, will offer my educated guess.

I doubt it will make any difference. The System scans the expansion I/O as a complete set, so it should take the same amount of time to collect all the I/O data regardless of what order the modules are placed. With modules like the ATC8, the main source of delay is the module itself, not the update rate back to the PLC.

From my experience (and by reading the datasheets of the modules), using the remote I/O is definitely not as fast as the Snap-in modules.

If it is critical to get much better speeds, one suggestion is to put a snap module on the V570, and use a couple of V230 with Snap modules, linked by UniCAN to the V570.

Another alternative is to use 3rd party I/O modules, on CANOpen or ModbusTCP. Just check the conversion time of those modules also.

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  • MVP 2023

For that kind of speed on that many channels you're going to have to buck up. I Googled this for a bit and this is about all I found:

Acromag Ethernet Analog

It updates all its channels in 10ms, for a measly $1700. You probably don't want to spend that much, but my experience is that high speed analog is not cheap. I've actually abandoned the PLC solution and gone to LabView with National Instruments PCI boards when I run into an application with these kind of demands. This was a hard-learned lesson, as the first time I ran into it I spent a over a month trying to make to make something work that was just not capable. Going that fast also makes the problem of noise much larger, but that's a story for another day...

The remaining question is whether the PLC can get the data every scan over Ethernet using Modbus TCP.

Just out of curiosity, what are you doing that requires such speed?

Joe T.

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