Operational Cases For Mesa - Nuvation Energy NUV300-BC-12 Product Manual

8.1.4.4. Scale Factors
All MESA points are integer values (signed or unsigned). To account for different range values beyond
the data size (i.e. greater than 65535 for an unsigned 16 bit value) or some fractional value (i.e.
1.1), some MESA points have scale factors associated with them. The scale factor is another point
within the model which contains a signed integer exponent of base 10 that scales a corresponding
point value. For example, a scale factor of 2 would result in multiplying the corresponding point by
100. Likewise a scale factor of -3 would result in a scale factor of 0.001. Refer to the prior MESA Draft
3 spreadsheet for the relationship between MESA points and their scale factors. All scale factors are
fixed for a model and do not change in value.

8.1.5. 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).
These two operational cases will be discussed in detail in the following sections.
8.1.5.1. 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 32. 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:
Document ID: NE-PM-002
Nuvation Energy Low-Voltage BMS - Product Manual
Address Scale Purpose
Factor
40086 No BMS Heartbeat counter incremented every second
40101 No Bit field of all faults/warnings of a the BMS
40105 Yes External DC voltage of the battery system
40106 Yes Charge current limit calculated by the BMS
40107 Yes Discharge current limit calculated by the BMS
40127 Yes Total DC current of the battery system
141 Rev 1.2, 2021-03-03
Curie Update 1