How many server can be read by 800xa abb client system
There is no physical limitation to how many OPC DA Connector service providers any given 800xA server can host as long as RAM/CPU resources are sufficient.
However, for obvious reasons a finite number has been used in product testing and certification. The System Guide document tells what limits any given version of 800xA has been certified for.
Some OPC servers are mutually exclusive and may prevent another to coexist in the same server, eg MOD300 and 800xA for Advant Master.
I would be surprised if ten light weight OPC servers would have problem sharing the same server, but I doubt it has been formally tested and approved.
When found appropriate, 800xA product management may agree to exceed the formal limit by granting a so called Temporary Sales Authorization request. Please speak to your regional sales representative if you seek a formal grant to exceed the System Guide.