Specifications

Halogen Gas Monitor – Multi Zone
Instruction 3015-5074 17
Connecting Communication Devices
Remote Display Module (HGM-RD) Connection
The HGM-MZ is connected to the HGM-RD using a shielded twisted pair instrument cable. The maximum
distance between the farthest away HGM-MZ and HGM-RD is 4500 feet.
Use any of the remaining service knockouts to gain access to the interior of the monitor. The RS-485
communication wiring between the HGM-MZ and HGM-RD must be connected in the following manner:
Locate the RS-485 connector in the HGM-MZ (page 15). Connect one lead of a twisted shielded pair to
the “B” connection point (the far right point), note the wire color. Connect the second wire to the “A”
connection point (the middle), note the wire color. Connect the ground to the “
” connection point
Locate the RS-485 connector marked “TO MONITORS” in the HGM-RD (See this topic in the HGM-RD
manual 3015-5157). This connector is located on the bottom of the HGM-RD PC board, second from the
right. Make the wire run to the HGM-RD and connect the twisted shielded pair to the RS-485 “TO
MONITORS” connector using the same color code as used on the HGM-MZ.
Integrating with Building Management Systems
The HGM-MZ may be connected directly to a Building Management System using a shielded twisted pair
cable. The cable from the Building Management System is connected to the RS-485 connector inside the
HGM-MZ. MODBUS RTU is the standard communication protocol.
Use any of the remaining service knockouts to gain access to the interior of the monitor. Locate the RS-485
connector and remove it from the circuit board. Secure the wire leads to the connector orienting them as
shown in the diagram below. Check to make sure that the polarity matches the wiring to the Building
Management System. When you are through securing the connections, carefully plug the connector back
onto the circuit board.
Larger Integrated Systems
You may also connect the HGM-MZ to a Building Management System through an HGM-RD. In this case,
first connect the HGM-MZ to the HGM-RD as described above. Then, follow the instructions in the
Communications Connections section of the HGM-RD manual (3015-5157) for information on how to connect
the HGM-RD to a Building Management System.
RS-485 Connector