BACnet Explorer Supports MSTP
CAS BACnet Explorer:
Available as a free tool for discovering, browsing, and testing BACnet devices.
CAS BACnet Explorer supports communication with BACnet MS/TP devices through the use of an external RS-485 adapter. This allows field technicians and engineers to directly connect a PC to an MS/TP trunk without requiring a BACnet/IP to MS/TP router.
By interfacing directly with the MS/TP network, CAS BACnet Explorer can be used to discover devices, inspect objects and properties, and perform basic diagnostic and testing tasks. This approach is particularly useful in commissioning, lab testing, and troubleshooting scenarios where router behavior may complicate analysis.
RS-485 Adapter Requirements
CAS BACnet Explorer communicates with BACnet MS/TP networks through a USB-to-RS-485 adapter that presents itself to the operating system as a virtual serial (COM) port. The software uses this virtual COM port to transmit and receive MS/TP frames over the RS-485 physical layer.
These adapters are widely available and relatively inexpensive. In general, any RS-485 adapter that installs as a standard virtual COM port should function correctly, provided that it supports the required baud rates and timing characteristics for MS/TP communication.
Direct MS/TP access can simplify troubleshooting by removing dependencies on BACnet routers and allowing engineers to observe device behavior directly on the field bus.
Example Adapter and Compatibility
The table below lists an example RS-485 adapter that has been tested with CAS BACnet Explorer in a lab environment. This is not an exhaustive list.
| Adapter | Manufacturer | Tested |
| USB-COMi-SI-M | USBGEAR | In lab (14 Dec 2006) |
Operational Considerations
When using CAS BACnet Explorer with an RS-485 adapter, proper MS/TP configuration is required. This includes setting the correct baud rate, MAC address, Max Master value, and network parameters to match the target MS/TP trunk.
Physical-layer best practices such as correct cable selection, termination at the ends of the trunk, and consistent grounding remain critical for reliable communication. The presence of a USB adapter does not eliminate the need for proper RS-485 network design.
For detailed configuration instructions and additional compatibility notes, refer to the CAS BACnet Explorer manual.
Community Feedback
While CAS BACnet Explorer is designed to work with standard RS-485 adapters, variations in hardware, drivers, and operating systems can affect results. Field feedback helps improve compatibility guidance.
If you have identified an RS-485 adapter that works reliably with CAS BACnet Explorer, you can share that information so it can be evaluated and documented.