Operational Cases For Mesa - Nuvation Energy S801 Product Manual

7.1.4. Operational Cases for MESA

There are two main operational cases for the control of Nuvation Energy BMS over its MESA interface:
1. An external controller (sometimes called "Energy Storage Controller") is used to coordinate power
control functions of the BMS in conjunction with some other equipment (such as an inverter). This
controller requires periodic and rapid responses of MESA point reads as well as some control over
the operation of the BMS (such as stack connectivity). If there is a loss of communication between
this controller and the BMS, the BMS will disconnect the stack(s) as a safety precaution.
2. An owner/operator of a battery system requires control of the BMS to monitor the activity of the
batteries and track battery usage and its charge/discharge activities. This information can then be
used to characterize the usage of the battery management system and to validate battery
warranties of a vendor.
Read and write Modbus TCP operations can be performed over the standard Modbus port 502 (only a
single connection is supported on this port).
In the scenario where the MESA interface must be accessed by multiple devices, the Multi-Stack
Controller provides a secondary port (11503) for read-only Modbus TCP operations.
These two operational cases will be discussed in detail in the following sections.
7.1.4.1. External Controller Communicating Over MESA Interface
An external controller typically polls Nuvation Energy BMS battery control points at a rate of 2–4 Hz.
This controller reads data points required to manage current flow in the system. The following table
summarizes the most important points an external controller may want to read from the BMS.
Table 8. MESA Points Read by an External Controller
Model Block Point Name
801 Fixed DERHb
802 Fixed Evt1
802 Fixed Vol
802 Fixed MaxBatACha
802 Fixed MaxBatADischa
803 Fixed BTotDCCur
A controller may also want to command Nuvation Energy BMS to perform certain actions, such as
connecting/disconnecting the battery. The following table provides the different writeable points in
the MESA interface for different control functions:
Table 9. MESA Points Written to by an External Controller
Model Block
801 Fixed
801 Fixed
802 Fixed
Document ID: NE-PM-004
Address
40086
40101
40105
40106
40107
40127
Point Name
ControllerHb
DERAlarmReset
BSetOperation
Nuvation Energy Multi-Stack Controller - Product Manual
Scale Purpose
Factor
No BMS Heartbeat counter incremented every second
No Bit field of all faults/warnings of a the BMS
Yes External DC voltage of the battery system
Yes Charge current limit calculated by the BMS
Yes Discharge current limit calculated by the BMS
Yes Total DC current of the battery system
Address Purpose
40087 Heartbeat register for external controller
40088 Clears all latched alarms in the BMS
40110 Commands Nuvation Energy BMS to connect/disconnect the
battery
55 Rev 2.0, 2022-05-18
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