Menu
Cimetrics
0
  • Home
  • Products
    • BACstac BACnet Stacks
    • BACnet MS/TP, B/IP & B/SC Routers
    • High-Density B/SC Diagnostic Hubs & Site CA
    • BBMD in a Box
    • Secured by Cimetrics™
    • BACnet Modules
    • BACnet Metering Gateways
    • BACnet Web Services
    • BACnet Explorer
    • Request Product Information
  • Services
    • For Building Owners
    • For Product Developers
    • For Facility Managers
    • Request Technical Support
  • About
    • About Cimetrics Video
    • Management
    • Vision
    • History
    • Our Technology
    • Our Customers
    • Case Studies
    • Career Opportunities
    • Terms & Conditions
    • Privacy Policy
  • Contact Us
    • Contact Us
    • Request Product Information
    • Request Technical Support
    • Security Center
    • Do not sell my personal information
    • Product Return Policy
    • Limited Hardware Warranty
  • Blog
  • Sign in
  • United States (USD $)
  • Your Cart is Empty
Cimetrics
  • Home
  • Products
    • BACstac BACnet Stacks
    • BACnet MS/TP, B/IP & B/SC Routers
    • High-Density B/SC Diagnostic Hubs & Site CA
    • BBMD in a Box
    • Secured by Cimetrics™
    • BACnet Modules
    • BACnet Metering Gateways
    • BACnet Web Services
    • BACnet Explorer
    • Request Product Information
  • Services
    • For Building Owners
    • For Product Developers
    • For Facility Managers
    • Request Technical Support
  • About
    • About Cimetrics Video
    • Management
    • Vision
    • History
    • Our Technology
    • Our Customers
    • Case Studies
    • Career Opportunities
    • Terms & Conditions
    • Privacy Policy
  • Contact Us
    • Contact Us
    • Request Product Information
    • Request Technical Support
    • Security Center
    • Do not sell my personal information
    • Product Return Policy
    • Limited Hardware Warranty
  • Blog
  • Translation missing: en.general.country.dropdown_label

  • 0 0

Troubleshoot MS/TP network. 6 reasons for troubled communication

February 08, 2018

Very often we see in the field or get a call from a customer complaining that not all MS/TP devices on their network are visible in their BACnet Explorer or some other network analysis program. Here are some suggestions from our MS/TP experts why you can’t see some devices on a MS/TP network and what to do about it.

1. The most likely reason is that the network is configured with a wrong termination value or the wrong number of network bias resistors.

2. All devices on the network may not be set to the same baud rate.

3. Some devices on the network are configured, or designed, to be MS/TP slaves, and therefore are not discoverable (unless you have an MS/TP slave proxy device).

4. Devices are not properly grounded

5. The wrong wire is used; for example, telephone cable is not appropriate cabling. Something like Belden 485 should be used.

6. There are too many MS/TP devices on one network. To be safe, the number of devices on an MS/TP network should be under 32.

HOW TO TROUBLESHOOT:

MS/TP network problems can be diagnosed using a  U+4 interface with with network monitor/analyzer software such as  BAS-O-matic network analyzer or a free software such as  Wireshark. Instructions on how to use the U+4 with Wireshark and/or BAS-o-matic can be downloaded from this here.

Begin troubleshooting by starting a BACnet Discovery Tool (e.g. BACnet Explorer). Capture for approximately one minute, then examine the captured packets to determine if there are "I-Am" packets from all MS/TP devices (BACnet Explorer broadcasts "Who-Is" packets, and all MS/TP devices should answer with "I-Am"). If the capture shows "I-Am" from some devices but the devices don't appear in Explorer, the problem is in Explorer; however , if the capture doesn't show "I-Am" packets from some devices, there is a problem with the network or devices (e.g. some devices have the same MAC address, or there is a problem with wiring). In this case try connecting only part (e.g. half) of the network and see if you see all the devices on this network. Then connect another part/half. If parts/halves of the network work separaately but together they don’t, most probably there are extra unnecessary network bias resistors or terminating resistors. Other causes can be a very long trunk; too many devices (more than 32) on one trunk; the connection is not properly grounded; or there are MAC address conflicts.

  • Share:

Leave a comment

Comments will be approved before showing up.


Also in Cimetrics News

June company news
June company news

July 01, 2025

New BACstac/DN Release + Smart Sensors for Building Efficiency & Training Opportunities

Read More

Cybersecurity News June 2025
Cybersecurity News June 2025

June 30, 2025


NIST flags rising cybersecurity challenges as IT and OT systems increasingly converge through IoT integration, FBI, cybersecurity firms say a prolific hacking crew is now targeting airlines and the transportation sector, Cybersecurity experts share practical advice for small businesses and more...

Read More

Cybersecurity news May 2025
Cybersecurity news May 2025

May 29, 2025

Midyear Roundup: Nation-State Cyber Threats in 2025, The Current Cybersecurity Landscape, Explained - J.P. Morgan, Why AI Is The New Cybersecurity Battleground and more...

Read More

Follow

Sign up to get the latest on sales, new releases and more…

© 2025 Cimetrics.
Powered by Shopify

American Express Diners Club Discover Mastercard Shop Pay Visa