Operating Instructions

Siemens Industry, inc. 60
RTU Programming and Scripting - Details
This section is intended for the programmer of the RTU or host system and includes
details about meter and element addressing, register locations, data formats and
protocol examples.
Register Organization
The MD-xxHD meter communicates through the reading and writing of registers. Registers are organized
into functional groups and are compliant with the SunSpec Modbus interface model.
SunSpec Common Registers
SunSpec TCP Network Stack Registers
SunSpec Serial Interface Registers
SunSpec Energy Meter
DENT Factory Registers
DENT User Command Registers
DENT User Configuration Registers
DENT Metrology Registers
DENT Waveform Capture Registers
The complete register set is included as an Excel file on the supplied thumb drive or at:
https://www.dentinstruments.com/siemens
Element vs. System Scope
Element
The term “element” is used in two contexts. Physically, the term Element is used to describe
groups of three channel sections identified by alphabetic letter on the silk screen of the PCBA
(such as A,B,C,D). In a three-phase power system these correspond to electric circuits. Logically
the term Element describes the scope of a data item, register or point (Modbus register or
BACnet object). Each Element based point is accessed by choosing the appropriate Modbus
address, BACnet object range, or BACnet structured view. Elements in turn have points that
refer to individual channels or to SUMS or AVERAGES of those channels. Registers that contain
data inclusive of more than one channel are identified as being either SUMS or AVERAGES of
the enabled channels within an element. In a BACnet structured view an Element represents a
level of organization for related points.
Channel
Channels are identified on the circuit board as CH1, CH2, or CH3 and represent physical CT inputs. In
three phase system configurations, these correspond to a current load on a corresponding line voltage. In
single phase configurations, they are just used to identify a CT location. Registers providing data for an
individual channel are also described as elements in their scope as a unique value exists for each Slave
Address or BACnet object instance.