Sorry for the delayed response...
What do you mean Batch Basic license? Is this a bundle license?
Each Batch Server needs a license and with this is included a Batch Client license.
Units (collection of Equipment Modules / Control Modules) are the number of the IUNIT_BLOCK instances.
See chapter 2.5.3 in the following manual for Batch Licensing details:
SIMATIC Process Control System PCS 7 SIMATIC BATCH Manual V7.1 SP1
I did not understand your last sentence regarding ES/OS.
Regards
Follow us on