Multiple Logix5000 controllers in a single rack

I have just been informed that we are using at least 2 controllers on a single rack for a controllogix5000 project. I have trawled the interweb and all I get is - yes you can. No instruction on how to configure, do I need to communicate between the cpu's to manage tasks etc.. Just hoping someone else has done this and might have some insight.

Thanks in advance

Kev

The ControlLogix 1756 series backplane has more than enough bandwidth for two controllers to function totally indpendently, so you could run them sharing nothing but the power supply.

But most folks end up sharing Ethernet or ControlNet cards between the processors; they're "bridges", after all, not "scanners".

The Controllers are running totally separate programs and have totally separate databases; it's not like with a multi-core CPU in your computer where they share or divide the workload.

Data sharing between processors can be done with Produced/Consumed Tags or with MSG instructions.

Frequently, Controllers in the same chassis will share Input connections, where one is a Listen-Only connection. This conserves network bandwidth and internal connection resources.

The principal "gotcha" is when you're using ControlNet; if you have multiple Controllers running scheduled connections across the same ControlNet bridge, both of them will have to go into Program Mode to change that schedule.

Hi

I have a system where I have 2 l63 and
1 l61 running and have no problems. The thing
To remember is that only one CPU is the time master ( ken please
Correct me I am wrong) and this would mean that only 1 processor
Would have to control motion if you have any. Also only 1 cpu can own a output
Card but a simple MSG or produced tag and you can turn them on from the other CPU.

Sorry about the line spacing working from phone

Donnchadh

Thanks for the info, interesting about the outputs - I will need to do a little more forward planning and differentiate the system into specific control areas by the look of it. - Many thanks for the replies.
No Controlnet Ken, but I am using devicenet.

Kev

Hi Kev

Glad to pass on my little knowlege :nodi: nothing to the help I have got here over the years.


From what I remember its the same with the device net scanner cards( 1 cpu is the owner) as that is how I set them up as I have just check the plc code on the 3 cpu's and that would sound correct to me as you could have 1 cpu turning and output on, and the other cpu turning it off.

Donncahdh