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Prepping for Installation
Connecting a Communication Cable
24
Building Technologies
125-202
06/06/2017
meter is configured for Modbus or BACnet mode, the MD series meter will
communicate over the Modbus protocol.
5. Select the PC COM Port from the drop-down list. For a USB connection, select
COM
xx USB in the field, where xx is the port number. For an RS-485 connection
using an RS-485 adapter, select COM
xx RS-485 Isolated Port (COMxx), where xx
is the COM port number.
Default settings are used for the two remaining fields: Data Bits is 8N1 and the Baud
Rate is 9600. When BACnet is selected as your protocol, an additional read-only field
displays the BACnet Device ID.
Setting the Network Address Switches
There are two rotary network address switches on a serial MD-BMS and MD-BMED
Power Meter, labeled MSB and LSB. These two switches are used to select the
BACnet/Modbus address the client uses to communicate with the MD-BMS and MD-
BMED Power Meters.
The rotary switches are 16-position, hexadecimal switches. The default factory setting
is hex 01. The address is a hexadecimal (hex) value, represented by the digits 0
through 9, and letters A through F. For example, a network address of 100 in decimal
is converted to 64 hexadecimal and set on the MD-BMS and MD-BMED by:
●
MSB switch—select 6
●
LSB switch—select 4
In some cases, the hex value may need to be converted to decimal when entered into
the RTU or data logger. See Appendix G for a hexadecimal conversion table.
The BACnet MS/TP MAC and Modbus address is a decimal value, represented by
three digits: 000 through 009, 010 through 090, and 100 through 999.
NOTE:
BACnet MS/TP masters only support addresses 001 through 127.
Table 2: BACnet Hexadecimal Address Availability.
Hexadecimal
Address
BACnet Address Availability
00
Reserved for resetting the MD-BMS and MD-BMED to Modbus mode with 9600
baud, 8 bit, 1 stop bit and no parity.
01-7F
Available (01/001 is the factory default setting).
80-FE
Reserved for BACnet slave devices.
FF
The rotary switches can be used to configure the communication protocol to BACnet
or Modbus as well as changing the baud rate if unsure of the current settings (MD
SERIES METERS only).