Boiler Parameter Worksheet
Appendix
43
3.0
APPENDIX
–MODBUS
®
INTERFACE
The ENVI
®
MODBUS
®
connection is available to interface with Building Management Systems. Harsco Industrial,
Patterson-Kelley offers an optional protocol converter that can translate the MODBUS
®
protocol into BACnet, Lon
Works
®
, and Metasys
®
N2 protocols that are often used by Building Management Systems. One converter translates
the protocol for multiple boilers. Depending on the secondary language determines how many boilers can
communicate on one converter.
Only qualified control contractors should access the MODBUS
®
interface menu.
MODBUS
®
configuration parameters are listed below.
Protocol
MODBUS
®
RTU
Supported MODBUS
®
commands
Read Holding register (0x03)
Write single Holding register (0x06)
Baud Rate
9600bps
Data Length
8
Parity
None
Stop Bits
1
Physical layer
RS485 (two wire)
MODBUS
®
REGISTER MAP
Address
Byte Type
Parameter Name
Formula/Data
0
HIGH
State
See State Table
0
LOW
Supply Temperature
Normal Temperature
2
HIGH
Return Temperature
Normal Temperature
2
LOW
DHW Temperature
Normal Temperature
4
HIGH
Header Temperature
Normal Temperature
4
LOW
Firing Rate
1 = min to 255 = max
6
HIGH
Flue Gas Temperature
Flue Gas
Temperature
6
LOW
HX Temperature
Normal Temperature
8
HIGH
Outside Temperature
Outdoor Temperature
8
LOW
Flame Signal
0x00 = no flame
0x80 = flame
10
HIGH
CH Setpoint
Normal Temperature
10
LOW
DHW Setpoint
Normal Temperature
12
HIGH
Boiler Operation
0 = Off, 1 = On
2 = Off & pump on
3 = On & pump off
12
LOW
High Outdoor Air Temperature
Outdoor Temperature
14
HIGH
Minimum Outdoor Air Setpoint
Normal Temperature
14
LOW
Low Outdoor Air Temperature
Outdoor Temperature
16
HIGH
Maximum Outdoor Air Temperature
Normal Temperature
16
LOW
Outdoor Air Shutdown Temperature
Outdoor Temperature
18
HIGH
Night Setback
Delta Temperature
18
LOW
Error Code
See Error List
Section 3.2 and 3.3