Mesa Model Structure And Nomenclature - Nuvation Energy S801 Product Manual

Nuvation Energy Multi-Stack Controller - Product Manual
includes the charge and discharge current limits. All mandatory points are implemented. The Modbus
address of this model is 40094.
7.1.2.4. S803
This model describes a lithium-ion battery in detail. Voltage, temperature, and current statistics are
available at the pack and stack level within this model. All mandatory and most optional points are
implemented. The Modbus address of this model is 40116.
7.1.2.5. End Model
This model marks the end of the implemented Modbus address space.

7.1.3. MESA Model Structure and Nomenclature

This section is a clarification of terms used to describe a MESA model. It is used to understand the
terminology in the spreadsheet presented in the previous section.
7.1.3.1. Points
All MESA models are a collection of points (i.e. Modbus registers). These points can be one or more
Modbus registers in length. By definition, each Modbus register is 16 bits wide. For points that are
larger than 16 bits, partial read accesses are not allowed. A Modbus read/write error is returned on
such an access.
7.1.3.2. Fixed/Repeating Blocks
MESA models are described as collections of Fixed and Repeating blocks of points. A Fixed block is a
set of points that is always defined and never changes in its size. A Repeating block describes a set of
related points (i.e. usually for a string of batteries) of which there could be multiple instances of the
Repeating blocks. The points within a repeating block are the same but these sets of blocks are
concatenated sequentially.
For example in the 803 model, there is a set of repeating blocks that describe data for a particular
stack/string of batteries. Accessing the 803 repeating block corresponds to using a stack/string index
(0, 1, 2, ...) to access the desired repeating block.
For a multi-stack Nuvation Energy BMS there are 36 stack/string repeating blocks. If a stack/string is
configured in Nuvation Energy BMS software to be installed, then accessing its 803 repeating block
will provide a valid Modbus response.
For stacks or strings that are not installed, accessing the corresponding repeating block will result in
an unimplemented point response. Repeating blocks are taken into account in the length indicated in
the model header.
7.1.3.3. Unimplemented Points
Any MESA point that is not implemented by a vendor will generate an unimplemented response. The
response will be a valid Modbus read response but all point data returned will report unimplemented
Document ID: NE-PM-004 53 Rev 2.0, 2022-05-18
Curie Update 3