7 ModBus (continued)
Indirect Plate Water Heater Installation & Service Manual
Primary Data Tables
Table Data Type Read / Write
Input Registers 16-Bit Word Read Only
Holding Registers 16 Bit Word Read / Write
Input Registers
Address Description Default Unit Min. Max. Resolution
30003 Outlet Temperature ---- Degrees Fahrenheit -328 1562 0.1
30005 Inlet Temperature ---- Degrees Fahrenheit -328 1562 0.1
30007 Outlet Voltage (Valve Position) ---- Volts 0 10 0.01
Holding Registers
40001 Setpoint 118 Degrees Fahrenheit 90 180 0.01
Memory Map
23
RS-485 Communication Bus
• Maximum Length = 4000 feet
• Cable Specification = 24 AWG / A,B (twisted pair) and GND Shielded, with characteristic Impedance = 120 ohm
• Maximum Load = 32 units (32 nodes)
NOTE: Cable must be terminated with 120 ohm impedance matching resistor on each end.
Physical Wiring
Figure 7-2_Wiring Diagram
Mixed Inlet
Temperature
Domestic Water
Outlet Temperature
Auto Reset High Limit
Splice
Splice
Splice
Internal
Recirculation
Pump 120
VAC 60 Hz
S
w
i
t
c
h
RTD
RTD
Ground Lug
BLUE
YELLOW
BLUE
BLACK
WHITE
GREEN
ORANGE
ORANGE
GRAY
BLACK
WHITE
GREEN
GREEN
ORANGE
ORANGE
BLACK
BLACK
WHITE
GREEN
BLACK
G
R
E
E
N
W
H
I
T
E
ON
3
2
1
1
2
3
4
+
_
OUTPUT
INPUT
L
N
L
N
2
1
COM 1
2
WHITE + -RED
THERMO
COUPLE
(OUTLET)
Boiler Water
Modulating Valve
Mounted Inside Control Box
Transformer 120 VAC/ 24 VAC
BUILDING
MANAGEMENT
SYSTEM
A
B
SHIELD
1A
1B
1C
1D
2A
2D
2C
2B
3A
3B
3C
3D
IO Module 3
IO Module 2
IO Module 1
Comms Channel 2
Comms Channel 1
HA
HB
HC
HD
HF
HE
JA
JB
JC
JD
JE
JF
L
V-
V+
VI
AC
AB
AA
N
D8
LB
LC
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