RLE Technologies BMS-LD3Z Three Zones of Integrated Leak Detection


Installation Supplies

Included with the BMS-LD3Z
BMS-LD3Z device

Available from RLE, sold separately
24VDC power adapter Leak detection cable, LC-KITs, and spot detectors as necessary for your application

Additional Supplies
18AWG shielded twisted pair stranded copper wire – no more than 2000ft (610m) (Modbus RTU or BACnet MS/TP communication via RS-485 port)

Mount the Device

The BMS-LD3Z is designed to be installed in a panel, on a DIN rail, or mounted on a wall.

  • If you’re installing it on a DIN rail, use the DIN rail clip and secure the unit appropriately for your application.
  • If you’re mounting the unit on a wall, use a screwdriver to loosen the three screws and remove the DIN rail clip from the back of the unit. Then use the keyhole slots and secure the unit to the wall.

Power the Unit

The BMS-LD3Z is designed to accept hardwired 24VDC power through the power terminal block (TB2). If hardwired power is not available, purchase and install RLE’s PSWA-DC-24 power supply.

Leak Detection Sensing Cable

Since leak detection sensing cable cannot connect directly to a controller, a leader cable is used to connect each separate zone of leak detection cable to the BMS-LD3Z. For each zone of leak detection:

  1.  Insert the stripped wires of the leader cable into the appropriate slots in the terminal block – from left to right: white, black, green, red. Tighten the screws to secure the wires.
  2.  Unscrew the EOL from the end of the leader cable.
  3.  Attach the length of sensing cable to the leader cable.
  4.  Route the sensing cable according to your cable layout
  5.  Secure the EOL to the unoccupied end of the sensing cable.
  6.  Repeat steps 1-6 for each zone of leak detection.

Set the DIP Switches

The BMS-LD3Z has two sets of DIP switches. Push the numbered switch to the right to turn it on; push the switch to the left to turn it off. DIP switch 1 is used for system and communications configuration. DIP switch 2 is used to set the unit’s device address.

DIP Switch 1, switches 1 through 8
SW1 and SW2 – Set the baud rate for the EIA-485 Port – 8 bit, no parity, 1 stop bit.
1 = Off 2 = Off 9600 baud
1 = On 2 = Off 19200 baud
1 = Off 2 = On 38400 baud
1 = On 2 = On 76800 baud
SW3 – Modbus RTU or BACnet MS/TP Selection
3 = Off Communication via BACnet MS/TP
3 = On Communication via Modbus RTU
SW4 – Modifiable BACnet Instance (For advanced users only)
4 = Off BACnet instance set via DIP switch SW2 (default)
4 = On BACnet instance set from the command line. Refer to the BMS BACnet Instance

Modification Technical Guide for complete instructions.

SW5 – Zone 1 Leak Detection – Enable or disable leak detection for Zone 1.
5 = Off Leak detection is enabled. (Default)
5 = On Leak detection is disabled.
SW6 – Zone 2 Leak Detection – Enable or disable leak detection for Zone 2.
6 = Off Leak detection is enabled. (Default)
6 = On Leak detection is disabled.
SW7 – Zone 3 Leak Detection – Enable or disable leak detection for Zone 3.
7 = Off Leak detection is enabled. (Default)
7 = On Leak detection is disabled.
SW8 – Leak Alarm Delay – The amount of time that elapses between the time a leak is detected and when that leak is annunciated.
8 = Off 10 seconds (Default)
8 = On 120 seconds

Use DIP switch 2 to set the address of the device. This should be a number between 1 and 254. Adjust the individual switches until their sum equals the device address. Switch values are as follows:

Connect the BMS-LD3Z to the Network

The BMS-LD3Z needs network connectivity to communicate with a Modbus RTU or BACnet MS/TP system, such as a BMS. Use a 2-wire RS-485 cable to connect the BMS-LD3Z to the network through the wiring connection at TB1. RLE recommends an 18AWG shielded twisted pair stranded copper wire for the connection, using no more than 2000 feet (609.6m) of wire at this specification. If longer runs are needed, please contact RLE.

After the BMS-LD3Z is connected to the terminal (115200 bps, 8 bit, no parity 1 stop bit) you’ll see a menu that can be used to help understand the BMS-LD3Z’s settings and functionality. Commands available from this menu are:

Command Action
slist List all sensors
settings Show current system settings (set by dip switches)
bid Show BACnet device ID in use
sbid Configure custom BACnet device ID
reboot Reboot unit
? Print main menu

Modbus Communications

The BMS-LD3Z uses its RS-485 port to communicate via Modbus. The BMS-LD3Z is configured to act as a Modbus Server device on a common network and is a Server only device – it will never initiate a communications sequence.

Read Registers
To read the BMS-LD3Z’s parameter values, the Client must send a Read Registers request packet (function code 03 or function code 04).

Register Name Description Units Range
30001 Status Bit Level Status – as follows:

0x01 (1) = Zone 1: Leak Detected 0x02 (2) = Zone 2: Leak Detected 0x04 (4) = Zone 3: Leak Detected 0x100 (256) = Zone 1: Fault Detected 0x200 (512) = Zone 2: Fault Detected 0x400 (1024) = Zone 3: Fault Detected

None 0-65535
30002 Leak Current Zone 1 Leakage current on cable μAmps 0-65535
30003 Leak Current Zone 2 Leakage current on cable μAmps 0-65535
30004 Leak Current Zone 3 Leakage current on cable μAmps 0-65535
30010 Version Firmware version xx.xx X 100 0-65535
40009 Number of Zones (3)

BACnet Communications

BACnet auto-discovery can be used to find all BACnet data points available for the 1-wire sensors. BACnet MS/TP objects are as follows:

Object Description Object Description
BI:X01 Zone X Enabled
BI:X02 Zone X Leak Detected AI:X02 Zone X Leakage Current
BI:X03 Zone X Cable Break

Directions for modifying the BACnet instance, intended for advanced users, can be found in the BACnet Instance Modification Technical Guide.

System Reference

Front Panel LED
The lower right corner of the BMS-LD3Z houses an LED that uses different colors and blink patterns to convey device status and information.

Leak Detection Zone Status LEDs
The LEDs next to the three leak detection leader cable connectors across the top of the device light to indicate the leak zone’s status:

Front Panel Push Button
A white button in the lower right corner of the BMS-LD3Z can be used to perform a factory reset of the device:

Operation Function
Press and hold for 20 seconds, then release the button (Red LED will turn ON after 10 seconds and then turn OFF after an additional 10 seconds) Perform a full factory reset of the unit. Any stored BACnet settings will be deleted.

BMS-LD3Z Physical Diagram

Documents / Resources

RLE Technologies BMS-1WIRE Plug-And-Play Temperature And Humidity Monitoring [pdf] User Guide
BMS-1WIRE, Plug-And-Play Temperature And Humidity Monitoring, BMS-1WIRE Plug-And-Play Temperature And Humidity Monitoring


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