Rockwell Automation 1756-HIST2G Historian ME 2.1 - Manual (Page 278)

F ACTORY T ALK H ISTORIAN ME M ODULE U SER G UIDE
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
The maximum number of modules that can be used to transfer data
simultaneously from the ME to one SE server is 20.

The maximum number of clients that can have simultaneous access to the module
is 5. This number includes a web browser, the FactoryTalk Historian SE, and any
other client tool. After the limit is reached, any client will be denied access to the
module based on total number of connections exceeded.
Hardware
ControlLogix Chassis
This section lists considerations related to the ControlLogix chassis.

Connect up to a maximum of 4 controllers in the same ControlLogix chassis.

A maximum of 2 FactoryTalk Historian ME modules in a single chassis.

The module does not support a redundant controller chassis.
Once the FactoryTalk Historian ME module is running in a particular slot, Rockwell
does not recommend moving the module to a new slot because this may result in the
same tags being considered as different points.
Logix Controllers
This section lists considerations related to the Logix controllers.

The number of controllers that can transfer data to one Factory Talk Historian ME
is 4.

Data Collection should be stopped before creating tags to avoid creating excess
trend objects in the controller, consuming more controller memory.

The FactoryTalk Historian ME can only connect to the controllers in the chassis it
is placed in. This means it can only connect to ControlLogix controllers; it cannot
connect to either ControlLogix or other controllers in another chassis.
If the FactoryTalk Historian ME must connect to data in other chassis hardware
such as non-ControlLogix or third-party controllers, you can configure a
ControlLogix controller to act as a concentrator in the same chassis. This
controller can then be configured to expose the data from the remote controllers to
the Factory Talk Historian ME. However, it is critical to consider the increased
load that an extra data server will introduce in a ControlLogix system when
configuring Data Collection.