Specifications

The Clear Statistics command is redirected to the FEC Family BACnet Device used for collecting MS/TP trunk
statistics. If the device used for collecting statistics changes after this command is issued, the new device is not
cleared unless the command is issued again.
Sync Field Device Time(s)
The Sync Field Device Time(s) command sends a high-priority time synchronization command to all child BACnet
Integration devices, based on each device mapper object's Manual Time Sync Type attribute.
If the Manual Time Sync Type is set to:
• UTC: UTC time synchronization message is sent.
• Local: A local time synchronization message is sent.
• None: No message is sent.
• Auto: The mapper object's Protocol Services Supported attribute is used to determine which type of time sync
is supported, and if:
- utcTimeSynchronization is set, the code functions as if Time Sync Type is set to UTC.
- utcTimeSynchronization is not set and timeSynchronization is set, local time is set.
- neither utcTimeSynchronization nor timeSynchronization is set, an error is returned.
Analyze Field Bus
The Analyze Field Bus option has been modified on a Remote Field Bus to use BACnet services that can pass
through routers. (The local field bus operation can use MS/TP test messages, which do not pass through routers.)
In addition, the bus can only detect remote devices that answer the wild card device instance value of 4194303.
Some commonly used MS/TP devices do not respond to the wild card device instance value and are not detected
by this operation. Devices already mapped are always displayed.
Note: Running a bus analysis remotely requires significantly more time to complete than what a local field bus
requires, and adds significant message loading to the router while running.
End-of-Line Termination on the MS/TP Bus
Daisy-chained RS485-protocol networks typically require some type of end-of-line (EOL) termination to reduce
interference caused by signal reflection that occurs when data transmissions reach the end of a bus segment and
bounce back on the segment. The high baud rates on MS/TP bus applications require robust EOL termination and
strict adherence to the EOL termination rules. Figure 6 shows an example of the EOL termination settings on an
MS/TP bus application.
The EOL termination requirements for the FC bus are different from the SA bus requirements. See EOL Termination
on the Local FC Bus and EOL Termination on the SA Bus for more information.
Also, third-party MS/TP devices and TEC26xx Series thermostats have different EOL termination requirements from
Metasys devices on the FC bus. See TEC26xx Series Thermostats and Third-Party MS/TP Devices for more
information.
16MS/TP Communications Bus Technical Bulletin