HGM-MZ to N2 Communications Adapter
Rev 1 (P/N 3015-5514) 3
Figure 2 – HGM-MZ to N2 Communications Adapter: Wiring w/Remote Display
3. Field Hookup of N2 Communications
The “BAS BUS” (N2) RS-485 communications port on the adapter is electrically isolated from the HGM-MZ
and from earth ground. This prevents problems with potential differences in “ground” between physically
separate locations.
Connect the N2 ‘+’ wire to the BAS BUS N+ terminal block screw. Connect the N2 ‘-‘ wire to the BAS BUS
N- terminal block screw. Connect the N2 REF wire to the BAS BUS REF terminal block screw. Shield
connection practices vary. Refer to Johnson Controls Metasys N2 documents for Johnson-recommended
practices. Options are to hard-terminate the shield to the case, soft-terminate (through a small-value capacitor)
the shield to the case, or leave the shield floating.
If the adapter is the last device on the N2 line, the RS-485 TERM jumper just below the BAS BUS terminal
block should be installed. Otherwise leave the RS-485 TERM jumper disconnected.
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