Siemens MD-BMS - Appendix B BMS and MD BMED Power Meters Modbus Absolute;Net Value; Protocol Commands

Appendices
Appendix B
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MD
-
BMS and MD
-
BMED Power Meters Modbus Absolute/Net Value Measurement Registers and
Protocol Commands
86
Building Technologies 125-202
06/06/2017
Modbus Offset Register Description
47061 7060 Volts L3 to Neutral “
47062 7061 Time Since Reset LSW (Seconds) Seconds since kWh, kVAh, kVARh and
associated Demand registers were reset. LSW
(resettable).
47063 7062 Time Since Reset MSW (Seconds) Seconds since CAM. MSW
47080 7079 Negative kW System Average Equals Negative KWH_SYSTEM_L&M ÷
(TimeSinceReset_L&M seconds /3600
seconds/Hr) (resettable).
46081 7080 Negative kW Demand System
Minimum
Minimum Average power window (kW)
47082 7081 kVA Demand System Maximum Maximum Instantaneous kVA Demand (kW,
resettable).
47083 7082 kVA Demand System Now System Average kVA Demand for the most
recent (current) Demand Window (resettable).
47084 7083 kVAR Demand System Max System Maximum kVAR Demand (kVAR,
resettable). It displays the default value after a
CAM until one demand window elapses. After a
power cycle or CPU reset, the value is not reset
and does not update again until one demand
window elapses.
Protocol Commands
The Modbus messaging protocol used for communication follows the Modbus RTU
protocol described in this section. Each register read from or written to the power
meters is a 16-bit, unsigned, positive integer value. The MD-BMS and MD-BMED
power meters support the following commands:
Table 23: Supported Modbus Commands.
Command Name Command Number
(Hex)
Description
Read Holding Registers 03 Used to read the data values from the power
meter.
Write Single Register 06 Used to write a single holding register to an
MD-BMS or MD-BMED power meter.
Report Slave ID 11 Used to read information from the identified
power meter.
The following guidelines are used for these Modbus commands:
● All values are hexadecimal; spaces are not included.
● The address is the value of the address switch on the power meter. This must be
different for each power meter on a single Modbus network.
● The register’s high-order and low-order bits are the 16-bit value of a single, or first
register to be accessed for a read or write.
● The CRC is the 16-bit CRC value. Note that the CRC’s LSB and MSB are reversed
in comparison to those for the registers and data.