9 bacnet background, 1 background on "device objects, Bacnet background – Obvius BACnet User Manual
Page 48: Ackground on, Evice, Bjects
BACnet Server for AcquiSuite
Page 48 of 52
CVS:bacnet/Documentation/BACnet_Users_Guide.doc
9 BACnet Background
Here is a comparison between BACnet and Modbus concepts and terms:
BACnet concept
Modbus concept
"Object"
Register block (group of related registers)
"Property"
Individual register
"Device Object" (DO)
Register block containing Meter name, firmware version,
overall status flags, etc.
"Analog Input Object" (AI)
Register for individual data point
"Binary Value Object" (BV)
Register for individual relay output
"ReadProperty" (RP),
"ReadPropertyMultiple" (RPM)
ReadCoilStatus, ReadHoldingRegister, ReportSlaveID, etc.
"WriteProperty" (WP)
PresetSingleRegister
MS/TP (BACnet over RS485)
Modbus/RTU (Modbus over RS485)
BACnet/IP (BACnet over UDP/IP, default
port 47808)
Modbus/TCP (Modbus over TCP/IP, default port 502)
9.1 Background on "Device Objects"
A BACnet Device Object collects together information such as Description, Location or Firmware Version
related to a single device, such as the AcquiSuite itself, or each meter shared by the AcquiSuite.