Koyo vs CompactLogix Scan Time

[AMarks95]

I have an OPC Server (Kep) pulling tags from an AB 1769-L36ERM and a few different Koyo PLCs (450, 454).

On the HMI (FTV SE) there's one screen that's almost exclusively tags from the CompactLogix and one that's all Koyo. Both screens have the same update rate (0.1s). The values on the screen that is all CompactLogix seem to be much more instantaneous than the other.

Could this be caused by the difference in hardware? I would imagine the CompactLogix is more powerful than the DL454 and probably has a larger-bandwidth ethernet port which allows it to transfer data quicker.

 

[AlfredoQuintero]

If you really need to measure this accurately, I think you would need an Ethernet managed switch with mirroring port functionality and take Wireshark traces for the communication between each PLC and the respective HMI and do analysis of the traffic.

 

[sparky66]

What protocol is being used for each of those?

 

[cardosocea]

How's Kepware configured as well? And, as sparky mentioned, does the protocol allow for that refresh rate of values for the Koyo units?

 

[icky812]

The Koyo 400 series has a limited backplane speed compared to the CompactLogix. Think of it in terms of 8 bit computing vs 32 bit computing. There is about 25 years of design improvements in the CompactLogix comparatively.