Operating Instructions

51 Siemens Industry, Inc.
Protocol Verification
The network protocol is typically specified as part of the installation. BACnet MS/TP and Modbus RTU
are the two communication protocols that operate over an RS-485 serial network and BACnet IP and
Modbus TCP are the protocols over Ethernet. Each combination of interface and protocol require specific
registers settings described below. The scope of this section is to use either the LCD interface or
software tools to quickly confirm or change settings to match an existing specification. Further
information and optimization tips are covered in the section on RTU programming.
Modbus Settings
Modbus RTU Settings
Device Address: In a Modbus network, each device must be assigned a unique slave address. Valid
Modbus addresses are 1 to 240 (keep in mind the MD-48HD requires 15 addresses beyond Element A, the
MD-24HD requires 7 addresses beyond Element A, and the MD-12HD requires 3 addresses beyond
Element A). The slave address of the power meter sets the register address for ELEMENT A. Adjacent
elements B, C, D, and so on. are accessed by incrementing the slave address by 1. The slave address of
the MDxx-HD meter must be set to match the address expected by the RTU and is normally part of the
network specification. NOTE: The default address for Element A is 1.
Modbus TCP Settings
Modbus Port: The MD-xxHD meter uses the industry standard Port 502 for Modbus. This port number can
be changed.
BACnet Settings
BACnet Device ID: In a BACnet network, each device must be assigned a unique Device ID and is
common to BACnet MS/TP and BACnet IP protocols. Besides the standard ability to change this from
a BACnet explorer tool it may be changed via ViewPoint HD, MD-xxHD Web App, or LCD.
BACnet MSTP
Device Address: MD-xxHD meters are Master devices and as such must use MS/TP addresses in the
range from 0-127. This address must be unique on the network.
Max Masters: The default setting is 127 and does not usually need to be changed.
Max Info Frame: The default setting is 1 and does not usually need to be changed.
BACnet IP
BACnet Port: The BACnet default port is 47808 and does not usually need to be changed.
BBMD: The BACnet/IP Broadcast Management Device is set to 0.0.0.0 at default and can be changed
through a software tool to allow discovery across networks.
Pulse Outputs (Discontinued)
Early MD-48HD meters (Hardware revision H running firmware version 1.012) were equipped with 2 pulse
outputs. User feedback indicated that inputs would be more useful than outputs. In response to this, the
pulse direction was reversed on the MD-12HD and MD-48HD meters. Pulse Output functionality is no
longer supported. PCBs with terminals marked Pulse Outputs rather than Pulse Inputs do not have
functionality and should be left disconnected.