Rs485 Bms - Bradford White OmniTech BONH1250 Installation And Operation Instructions Manual

OUTDOOR
OUTDOOR
CH1/DHW1
Page 40
CH1/DHW1
CH2/DHW2
7.E.12 RS485 BMS
CH2/DHW2
DHW/DHW3
BMS – if communicating to the unit via RS485 serial
DHW/DHW3
communications, either Modbus or BACnet MSTP,
SPARE 1
connect to terminals 60, 61, and 62 (Figure 13 on
page 36. Use 2-wire twisted pair, shielded w/drain
SPARE 1
(communication cable) between units. Connect one
SPARE 2
wire of the communication cable to A (-), terminal 61,
SPARE 2
and the other wire to terminal B (+), terminal 60, and a
BAS 0-10VDC
third conductor to GND, terminal 62 (see RS485 NOTE:
BAS 0-10VDC
Grounding & Shielding).
PUMP 0-10VDC
Section 8.D.10.d on page 87 shows how these systems
PUMP 0-10VDC
are configured in the touchscreen controls.
RUN - C
RUN - N.C.
RUN - N.O.
ALARM - C
ALARM - N.C.
ALARM - N.O.
CASCADE - B
CASCADE - A
CASCADE - GND
BMS - B
BMS - A
BMS - GND
Figure 16. BMS Wiring Connections
RS485 NOTE: RS485 Grounding & Shielding
Grounding: To ensure that common mode voltage does not compromise the date, or damage the equipment, an extra
wire should always be used to connect the signal grounds. This means that a "two-wire" system actually requires three
conductors. Although it is possible to obtain cable with a twisted pair and a third conductor, it is simpler to use a cable
with an extra twisted pair and use one or both conductors for the signal ground.
Shielding: It is often difficult to make a clear determination as to whether shielded cable is required in an
application. Since the added cost of shielded cable is usually minimal, in most cases it is worth installing. If
shielded cable is used, the shield should be grounded at one end only, preferably to earth ground. It is not
recommended to use a shield drain wire as the signal ground.
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60
61
62
OUTDOOR 35
OUTDOOR 36
CH1/DHW1 37
38
CH1/DHW1
39
CH2/DHW2
40
CH2/DHW2
DHW/DHW3 41
DHW/DHW3 42
SPARE 1 43
44
SPARE 1
45
SPARE 2
46
SPARE 2
BAS 0-10VDC 47
BAS 0-10VDC 48
PUMP 0-10VDC 49
50
PUMP 0-10VDC
51
RUN - C
52
RUN - N.C.
RUN - N.O. 53
ALARM - C 54
ALARM - N.C. 55
56
ALARM - N.O.
57
CASCADE - B
58
CASCADE - A
CASCADE - GND 59
BMS - B 60
BMS - A
61
BMS - GND 62
OUTDOOR 3
OUTDOOR 3
CH1/DHW1 3
3
CH1/DHW1
3
CH2/DHW2
4
CH2/DHW2
DHW/DHW3 4
DHW/DHW3 4
SPARE 1 4
4
SPARE 1
4
SPARE 2
4
SPARE 2
BAS 0-10VDC 4
BAS 0-10VDC 4
PUMP 0-10VDC 4
5
PUMP 0-10VDC
5
RUN - C
5
RUN - N.C.
RUN - N.O. 5
ALARM - C 5
ALARM - N.C. 5
5
ALARM - N.O.
5
CASCADE - B
5
CASCADE - A
CASCADE - GND 5
BMS - B 6
BMS - A
6
BMS - GND 6