Modbus Rtu Wiring - Honeywell E-Mon Class 3200 Owner's Manual

E-MON CLASS 3200 METER

6.10 Modbus RTU Wiring

The E-Mon Class 3200 Modbus option meter communicates with building
automation equipment over a 2-wire (3-conductor) RS-485 network using
Modbus RTU protocol. The meters are networked in a daisy-chain configuration
with BELDEN 1120A cable or equivalent required. The cable rating of 600V allows
the RS-485 network to be connected to 480-volt meters. Up to 52 meters can be
installed on a network string. The maximum combined length of all daisy-chained
cables must not exceed 4000 feet.
The meter-to-network connection is through the 3-screw terminal which is
located on the Main Power Board of the meter. Tighten the terminals to 2.2 in-lb.
Fig. 18. RS-485 Terminal.
The meter is shipped with a Modbus ID number of 02. NOTE: Modbus address
must be changed to 01 for open protocol for BACnet (Optional) to function as
specified. This must be changed if the network has more than one meter
installed. The change must be done before the meter is introduced into the
network. The meter can be numbered from 1 to 247. There can be no duplicate
numbers on a network, so caution must be taken when assigning a meter ID
number prior to its installation on the RS-485 network.
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