Bacharach HGM300 Installation Manual page 5

Field Hookup of N2 Communications
The "BAS BUS" (N2) RS-485 communications port on the adapter is electrically isolated
from the HGM300 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.
Setting HGM Communication Address On Adapter
See Figure 4 for the location of adapter dipswitches A and B.
Switches 5-8 on the adapter's 'A' dipswitch are used to match the node address set on the
HGM's address dipswitch (on HGM main board). Values from 0-15 are possible:
HGM address
-----------------
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
Since the HGM is the only node on the adapter-to-HGM interface, address 1 is normally
used. Be sure to set the same address on the adapter and the HGM main board
dipswitches.
A5 A6
----------------------------------------------
Off Off
Off Off
Off Off
Off Off
Off On
Off On
Off On
Off On
On Off
On Off
On Off
On Off
On On
On On
On On
On On
5 of 10
A7 A8
Off Off
Off On
On Off
On On
Off Off
Off On
On Off
On On
Off Off
Off On
On Off
On On
Off Off
Off On
On Off
On On