// when it does not work
The router's status page tells you
| What you see | Why | What to do |
|---|---|---|
| MNSM stays SoleMaster or PollForMaster; Next Station is the router's own MAC | The router hears no other master: baud rate, polarity, SC not connected, no termination, or only slaves | Check baud and wiring; the LEDs flash whatever the polarity or baud |
| Devices found, every read times out | The client reads from the router instead of through it | A client that uses the routing (BACManager 1.4.6 or later) |
| BIP packet count far above MS/TP count | Messages are not being routed | Same: the client is not using network numbers |
| Next Station keeps changing; devices drop in and out | Duplicate MACs, a neighbour leaving the token, Max Masters not matching | Unique MACs from 1 up; the same Max Masters everywhere |
| Many Invalid Long Frames | Bias or termination | Jumpers in at the end, out in the middle, 120 Ω at the far end |
| Two routers, devices vanish | Same MS/TP network number, or instance 0 on both | A unique MS/TP network and device instance on each |
| MS/TP slaves (MAC 128+) not found | BASRT-B talks to slaves but cannot discover them | Address them directly, or a BASrouterLX with slave proxy |
| Nothing from another subnet | No BBMD, or BDT entries missing on one side | One BBMD per subnet, each listing the others |
The BASrouterLX adds 115200 baud, slave proxy and automatic slave discovery, an MS/TP backbone between IP networks, and a capture of MS/TP frames for Wireshark. Contemporary Controls' own free BACnet Discovery Tool works only on UDP port 0xBAC0; if it sees the MS/TP devices, the router is doing its job. Their manuals and notes are on ccontrols.com.
