Estimation of needed PLC type for 800xA
Is there method to estimate which PLC type one needs for 800xA on pre-project stage?
For example, would be enough PM861 if I have 100 loops with 250 msec cycle and 300 analog measurement+100 binary inputs with 500 msec cycle?
This is never an easy answer. The IO is just a small part of the load on a controller. Other things to consider is: How many PID loops, how fast they be executing, inter controller comms (how many, data types, etc), interlocking code, other complex control code, .... I think you get the picture.
If you can answer these questions then the controller needed, such as PM861, PM864, PM866, PM891 would be resolved.
Attached is a rough guide. Please do not use as an exact tool, as the above issue would also need to be brought into the calculation.
Following to my question - 100 loops with 250 msec cycle (100 AI with status + 4 limits each and 100 AO with status), 300 analog measurements (300 AI with status + 4 limits each), 100 binary inputs (100 DI with 2 limits each) with 500 msec cycle. Assume it is 2 applications (1st - loops, 2nd - monitoring) for single PLC without communication between PLCs (there are no PLC partners). Is it possible to estimate which type of PM I need?
You can also ask your local ABB sales contact to provide you with the Wizard tool for System 800xA. The wizard is a tool were you can create your system layout and also make a rough estimation of the controller load.
The Wizard is also available at the ABB Partner Portal. If you are a first time user, pls register at www.abb.com/myabb
The Wizard tool will be located under this link:
thanks for reply. I have wizard tool and use it. But it, from my point of view, gives dramatically rough estimation in functions calculation and leaves choice on user. This choice is not simple - I think, you know price of CPUs and their license. Sure, that there is some Excel table like Digivis calculation tool for precise estimation.
thanks for your reply. I understand that forum is not place to make technical decisions, but to help others make such decisions. Beleive, I'm not in waiting that you will point me on PM type for above mentioned example. Wizard calculates my example as PM861 is enough. I calculated rough loading of PLC for my example (100 loops and 300 analog measurement+100 binary) as (if my calculation is wrong - please, let me know):
1) Loops: 100*SignalInReal + 100*PIDLoop + 100*SignalOutReal
2) Control: 300*SignalInReal + 100*SignalInBool.
Taking in account information from 3BSE041434-510_en_System_800xA_5.1_System_Guide_Technical_Data_and_Configuratio
n.pdf (from p.112) memory in PM861 is not enough. So, there is a collision between my and Wizard's calculations. Take in mind, that my calculation does not consider loading from ModuleBus, cycle time etc. So, I think (I hope) that in addition to Wizard there is some tool (probably Excel tables) for precise estimation of PM type, considering all of details (see Section 3 of 3BSE041434-510).
P.S. Wizard - perfect tool for creating configuration and getting some output documents.