AERCO Esteem Boiler with EZ-Set Controller - Manual (Page 169)

GF-135 Esteem 399 Low NOx Boiler
Chapter 18
OMM-0089_0A Installation, Operation & Maintenance Manual Controller Operation
18.9.15 Modbus Interface
The Modbus Interface allows a Building Management System (BMS) to directly connect to the
boiler. A BMS can read information from the boiler to determine its operating state, lockout
status, sensor readings, etc. A BMS can also operate the boiler by providing a setpoint.
Table 18-8: Modbus Configuration
Protocol
MODBUS RTU
Baud Rate
38400bps
Data Length
8
Parity
None
Stop Bit
1
Physical Layer
RS485 (2 wire)
Table 18-9: Supported Commands
DEC HEX Description
03 0x03 Read Holding Registers
04 0x04 Read Input Registers
06 0x06 Write Single Register
16 0x10 Write Multiple Registers
17 0x11 Report Slave ID
Table 18-10: Holding Registers (Read/Write)
Address
DEC (HEX)
Supported
Commands
Description
Byte:
Format
Notes
512
(0x00200)
0x03
0x06
0x10
CH Demand
MB:U8
LB:U8
Writing:
0= Modbus CH1 Demand has priority
over a DHW call.
255 = DHW call has priority over a
Modbus CH1 Demand.
Reading:
0 = No CH Calls Present.
255 = CH1 or CH2 Call Present.
Writing:
0 = End CH1 Demand.
255= Begin CH1 Demand.
A CH1 Demand lasts for 30 seconds
from the last successful write.
513 (0x201)
0x03
0x06
0x10
Maximum
Firing Rate
LB:U8
Value = Maximum Firing Rate %. This
register becomes active when 255is
written to register 512 (0x0200)
Page 169 of 188 AERCO International, Inc. • 100 Oritani Dr. • Blauvelt, NY 10913 OMM-0089_0A
MC1 06/19/14 Ph.: 800-526-0288