AC800M Controller load calculation
Is there any way to calculate the system load on the controllers , customer specification is system load should not cross 50%.
Controller Type planned in PM891.
6 remote clusters with Multimode connections
Program execution is 1 Sec
I/o scanning can be 500msec or more as hard wired signal are not so important , as not logic only for alarm.
Modbus interface with two sets of CI867 card to RTU560 total 2600 Signals to be exchanged - All CMUs need to communicate parallel redundancy is achieved through application .
Controller Type planned in PM891.
6 remote clusters with Multimode connections
Program execution is 1 Sec
I/o scanning can be 500msec or more as hard wired signal are not so important , as not logic only for alarm.
Modbus interface with two sets of CI867 card to RTU560 total 2600 Signals to be exchanged - All CMUs need to communicate parallel redundancy is achieved through application .
Asked 6 months ago
Answers
2
From ABB library, download the ac800m cpu load calcuation excel sheet and check it out.
http://search.abb.com/library/Downloa...
http://search.abb.com/library/Downloa...
Answered 6 months ago
1
Hi,
Your question is too general.
There is no information of total number and the type of IO modules in remote clusters. You mentioned 2600 signals trough CI867 but not describe the type of signals - digital or analog. Finally, what type of application - what you are going to do with the signals - calculations, control or only monitoring.
In AC800M there are defined cyclic load and total load. Generally the cyclic load is limited to 70-80% and the total load could be 100% without the problem. There are many posts here in AKS about that issue - have a look.
The cyclic load is manly affected by functions (application) and task time of application. Redundancy also decrease a little bit the total performance of CPU's.
The PM891 is the most powerful CPU from AC800M series, so in case it has not enough power for your needs, you can divide the application in two or more CPU's.
Your question is too general.
There is no information of total number and the type of IO modules in remote clusters. You mentioned 2600 signals trough CI867 but not describe the type of signals - digital or analog. Finally, what type of application - what you are going to do with the signals - calculations, control or only monitoring.
In AC800M there are defined cyclic load and total load. Generally the cyclic load is limited to 70-80% and the total load could be 100% without the problem. There are many posts here in AKS about that issue - have a look.
The cyclic load is manly affected by functions (application) and task time of application. Redundancy also decrease a little bit the total performance of CPU's.
The PM891 is the most powerful CPU from AC800M series, so in case it has not enough power for your needs, you can divide the application in two or more CPU's.
2
In addition to Kstoilovs answer. For low scan rate IO like this where speed does not matter you should use profibus.
Scanning of profibus IO signals takes zero - Yes, zero, percent CPU load. Which will be a very significant saving over using modulebus. The profibus IO modules are scanned by the CI854 direct to shared memory with the main CPU. You must still allow CPU load to process any function blocks connected to that IO.
Scanning of profibus IO signals takes zero - Yes, zero, percent CPU load. Which will be a very significant saving over using modulebus. The profibus IO modules are scanned by the CI854 direct to shared memory with the main CPU. You must still allow CPU load to process any function blocks connected to that IO.
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