beoengineer

Citect and Multiple PLC's, How many connected PLCs is reasonable?

5 posts in this topic

Hi, I'm wanting to know from anyone using Citect 7.X and above, about how your systems are set up when using a primary/secondary redundant server setup. With the advice from some consultants I've changed from a couple of stand alone units to a redundant server setup and multiple clients plant wide. There's about 8 PLCs currently with more coming. However it was recommended to split the IO server of Citect over the two physical servers, so that 1 physical server is the Primary IO server for 4 PLCs and secondary server for the other 4, then the other physical server has the same setup just opposite Primary/Secondary setup for the devices of the first physical server. I get that it splits the work load, but our engineering team is updating the servers multiple times a day most days and we will be for at least the next year, I'm finding that this system isn't very friendly constantly shutting down and restarting etc interrupting trending also, and want to switch from this split IO Server setup, to just one server that's primary, one server that's secondary. My Question, is it fine for one physical server to be primary and for how many PLC's? Server is a 6 Core Intel 2011 socket CPU (Not sure on exact specs at this stage). System INFO TAG count is about 5000, and Manufacturing is a slow process so no need for split second updates on anything. about 500 Trends polling every 1 second. Cheers.

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I did a job at a power station years ago and there was not even a secondary server. Thre were 11 PLCs running into Citect using the Omron FINS driver. The comms were Sysmac NetLink. It worked really well. About 4500 tags. That being said I have one at present also with just a primary server and one Omron PLC is the gateway to Citect - FINS driver again on Ethernet. There are another 10 PLCs in the system all with remote I/O off them - many remotes off the gateway PLC. Comms between the PLCs are on Controller Link - very fast - and the remotes are all on CompoNet - also extremely fast. Ethernet I/O is way slow when you load the system up by the way. CompoNet works on a twisted pair. About 2500 tags so far and growing. There are also a whole heap of power monitors to come straight into Citect - Modbus TCP - in the future. The later versions of Citect are slower than the older versions due to added functionality I guess. It is working quite well though. Do not know how it will go when everything is added in - time will tell.

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Hi, We have approx 75 PLCs on site with at least 65 of them on the network and over 40,000 tags in v6.10. They talk to the primary server as their primary IO Server. We have a redundant secondary server but, as we upgrade to v7.50, are moving to a distributed architecture, keeping the primary and secondary but including the ~15 PCs around site which are currently running as standalone servers (unnecessarily doubling polling of the associated PLCs) as IO servers for the local PLCs. The servers are 24 core Xeons w/4GB RAM. The new ones are a fair bit more powerful. Your Citect servers should be for running as Citect servers and little else. Development should be done on a separate PC. People should not be working on the servers or restarting them multiple times a day. That is madness. Two redundant servers is probably all you need in your situation, preferably in separate locations. You can share the load over the two servers if you're overloading the primary server.

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If you are concerned with connection limitations, you may want to consider incorporating an OPC server such as Kepware's KepserverEX. More information is available from our web site regarding its capabilities: http://www.eternity-sales.com/Kepware/kepserverex.htm Should you have any additional questions, feel free to email me through the link below, or our web site. Disclosure, ESI is an authorized Kepware Distributor.

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The issue is not connection limitations here - it is speed and how it all works. Citect did Olympic dam with over a million tags - 10 servers I believe. Scan time wa under 2 seconds - pretty impressive! I try to use direct drivers wherever I can as they work much better than OPC drivers form my experience if properly implemented. A friend of mine has over 150000 tags in Citect withe Siemens PLCs and the drivwer fron South Africa - it works like a charm - he gave away OPC as well - OK for a smallish number of tags.

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