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AJ Melb

Write throughput issue with ML1100/Rslinx/OPC

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Hello forumers, I was wondering if anyone has had peformance issues in writing data to ML1100 PLCs? The system we have is 3 (eventually 20) Micrologix 1100 PLCs connected to a SCADA system via rslinx 2.5 and OPC over ethernet. After a bit of bumbling around to configure the OPC (ML1100 documentation is a bit scanty) I have it working fine for reads using: Ethernet/IP Driver (should this be Ethernet Devices?) SLC-503+ plc (as there is no entry for ML1100) Polled Messages at 1000ms (default) Communications Time-Out 5s Maxium Packet Size (ethernet) Update Hotlink after a poke I've fiddled wth the ML1100 channel 1 "Message Servicing Selection / Comms Servicing Selection" - both normally left ticked. For clarity all the SCADA data is stored in a single int file (N9) and varies from 40-100 registers per PLC. These are polled at 5sec intervals and Active DDE/OPC topics and Communication Events show the topics - 1 per PLC healthy. The PLCs do talk amongst themselves - a couple of MSG polls peer-to-peer each with a 1sec delay timer on each .DN or .ER A problem arises when I attempt to write a few registers in quick succession to a PLC, either manually from SCADA points or programatically. The SCADA system (Honeywell's Experion) gets timeouts, but I can't see anything showing up in Active DDE/OPC topics or Communication Events. I'm guessing there is some throughput related parameter I haven't configured appropriately, as the server itself is idling (3% processor usage on task manager), and none of the PLCs have scan times >40ms (they are fairly packed). Timeouts like this were more an issue back in the days of 1200baud serial links, not full duplex 100MB ethernet. Any hints? As soon as I start fiddling with settings I find the interface stops working entirely (generally with terse parameter errors in Active DDE/OPC topics), and restoring rslinx from a backup seems to be the only way to fix things (resetting original values and rebooting the server does nothing), which slows testing a fair bit. Regards AJ

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Try this (see PDF below) ML1100CIPconfig.pdf

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Thanks for the link. Thats an interesting article, and one that appears useful for a niggling background problem I had - the RSLogix loader dropping out periodically, especially when doing online edits It doesn't unfortunately resolve the write errors I'm seeing though. I have gleaned a bit more information from Rockwell Knowledgebase & Tech support - SLC-503+ is the correct device to configure, and of the 2 interfaces that work (Ethernet Devices & Ethernet/IP driver) the Ethernet/IP Driver is the newer/preferred one to use. Still playing around with communications parameters and annoying Rockwell tech support - will see how I go.

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More information in case anyone else has a similar problem: 1) There is definetly something fishy about N9:124 and above. Rslinx gives parameter errors when when this address (or higher is used), but N7:124 and above have no problem. I thought this could be related to using SLC-503+ as the controller, but it too from the documentation I've found can have N9 configured with up to N9:254, so that ain't it. 2) My write throughput problem is a loading issue - I can identically configure other PLCs and have no problems with writes, as long as I keep the number of points being read lower. I am NOT impressed with Rockwell's scanty documentation.

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