Will the contoller load reduces if we used Profibus with S800 IO's instead of module bus.
Which is Better interms of contoller Load :
Modulebus - TB840's
Profibus - CI854 + CI840's
( AC800M Redudant configuraiotn - If any issues with link happens controller will go to fault mode and manual reset is required to get it back running)
Which is better interms of RIO distance limiation :
Modulebus - TB840's + TB825/826
Profibus - CI854 + CI840's ( With media converters Example:OZD Profi 12M G11 PRO)
Voted best answer
>"Will the contoller load reduces if we used Profibus with S800 IO's instead of module bus."
Yes. Profibus communications uses ZERO cpu time to collect and distribute IO signals. Everything is done by the CI854 module. With modulebus the controller CPU must also control the IO bus.
>"AC800M Redudant configuraiotn - If any issues with link happens controller will go to fault mode and manual reset is required to get it back running"
No. Profibus supports controller redundancy.
>"Which is better interms of RIO distance limiation"
Profibus. But always remember, the longer the distance of the copper cable the slower the profibus will run. Optical profibus segments allow very long distances without loss of speed.
By now you may wonder why anyone uses Modulebus. Module bus is generally faster, due mainly to the way that profibus scans the IO modules. It is also easier to maintain and cheaper to install in local cabinets adjacent to the controller.
Here's the manual you need ...
Just an adition to Robs answer.
If you set the modulebus io to scan as fast as possible (io scan on modulesbus 0ms) it will add 20% load to the total load of the controller. If you don't have much IO and your process is slow you can change this setting to what suits your application and you can get a lower perfomance penalty.
Module bus is designed for direct I/os means directly controlled by controller CPU & is designed when SOE are required so here i/o scan also come in to picture alibg with application scan so lower modulebus scan highet the cpu load & here as per design if any tb840 or fo cable link opens corresponding controller should go to fault mode so controller warm start required to get back the controller in line this design is best suited for ESD applucatiobs where less scan is required and profibus is designed to run remote I/os through profibus master, here I/o are connected indirectly to controller and it runs based on profibus speed between 1.5mbps to 12mbps but ensure higher the profibus cable length lesser the speed but here u can use profibus to fo converter and fo to profibus converter to go for long distance here there is double redundancy is there means profibus master redundancy, line redundancy and controller redundancy also there so on failing any profibus line or module will not cause any fault in controller fault so its best suited for long distance and for distributed applucations