MS/TP Physical Layer Bias and Termination
End-of-Line termination (120Ω) is normally applied at both ends of the MS/TP bus,
especially when using long cable segments and faster data rates. Fail-safe voltage
bias (200mV) ensures stable MS/TP operation. The BASrouterLX is shipped with fail-
safe voltage bias and EOL termination applied. Depending on the application, these
can be configured by removing jumpers inside of the case.
End Device
– In a router application where the location of the router is at the end of
the MS/TP bus segment – both bias and EOL termination must be applied.
Middle Device
–
In a router application where the location of the router is anywhere
between the end MS/TP devices (in the middle of the bus), termination jumper
should be removed. Fail-safe voltage bias jumpers could be left in place depending
on whether other devices on the MS/TP bus are providing additional bias or not.
Three configuration jumpers are located inside BASrouterLX’s case near the MS/TP
connector. Removing the BASrouterLX cover provides access to the 6-pin jumper
block.
The BASrouterLX is a high-performance BACnet router providing stand-alone routing
between BACnet networks such as BACnet/IP, BACnet Ethernet, and BACnet
MS/TP. Besides its high-speed processor, it has advanced features such as MS/TP
slave proxy support (allowing auto-discovery of MS/TP slaves) and diagnostic MS/TP
frame capture and storage for use with Wireshark®. Up to 50 BBMD and 147 FDR
entries can be made. The BASrouterLX has two physical communication ports — a
10/100 Mbps BACnet/IP Ethernet port and an optically isolated EIA-485 port for
MS/TP. Router configuration is accomplished using a resident web page.
•
Optically isolated MS/TP port
•
MS/TP baud rate range from 9.6–115.2 Kbps
•
MS/TP capture using Wireshark®
•
BACnet/IP Broadcast Management Device (BBMD)
•
Foreign Device Registration (FDR)
•
50 BBMD entries, 147 FDR entries
•
MS/TP Backbone
•
Allowlist
•
Backward Routing
Electrical (Class 2 Circuits Only)
INPUT
DC
AC
Voltage (±10%):
24 V 24 V
Power:
6 W
10 VA
Frequency:
N/A
47-63 Hz
Environmental
Operating temperature: 0°C to 60°C
Storage temperature: –40°C to +85°C
Relative humidity: 10–95%, non-condensing
Functional
Ethernet
MS/TP
Physical Layer:
10BASE-T EIA-485
100BASE-TX
Cable length limit: 100 m
1200 m
MS/TP data rate (Kbps): 9.6, 19.2, 38.4, 57.6, 76.8, 115.2 Kbps
MS/TP node limit: 254 devices total,
31 full-load devices per segment
Power Connection
The BASRTLX-B requires 24 VAC or 24 VDC while drawing no more than 10 VA of
power. The recommended conductor size is 16–18 AWG. COM is directly connected
to zero volts and the chassis is DC isolated from zero volts. Input connections are
reverse-polarity protected. See figure below for power options.
WARNING:
Internally, this device utilizes a half-wave rectifier and therefore can only share the same AC
power source with other half-wave rectified devices.
Sharing a common DC power source is also possible.
Sharing AC power with full-wave rectified devices is NOT recommended. Devices powered from a
common AC source could be damaged if a mix of half-wave and full-wave rectified devices exists.
BASrouterLX
BASRTLX-B
BACnet® Multi‐Network Router
Installation Guide
BASRTLX-B/P
Installation
