AERCO Modbus Communications Manual - Manual (Page 11)

Chapter 1
MODBUS
Communication GF-114
Introduction & Description USER MANUAL OMM-0035_0C
05/18/12 AERCO International, Inc. • 100 Oritani Dr. • Blauvelt, NY 10913 • Ph: 800-526-0288 Page 11 of 200
1.5 EXCEPTION RESPONSES
With the exception of Broadcast Messages, queries transmitted by the Master expect a normal
response from the addressed Slave on the network. However, if the addressed Slave cannot
process or interpret the message, it will respond with one of the Exception Codes listed in Table
1-4.
Table 1-4: Minimum Exception Code Set
Exception Code Description Comments
01 Illegal Function
The function code received is not valid or
is not supported.
02 Illegal Data Address
The data address received is invalid or is
not accessible due to security setting.
03 Illegal Data Value The data value received is not valid
1.6 PHRASES, ABBREVIATIONS & ACRONYMS
The phrases, abbreviations and acronyms used in this manual are listed in Table 1-5.
Table 1-5: Phrases, Abbreviations and Acronyms
Phrase, Abbreviation
or Acronym
Meaning
ACS AERCO Control System
ASCII American Standard Code for Information Interchange
BAS Building Automation System
Baud Bits per Second (bps)
BMS (BMS II) Boiler Management System (Boiler Management System II)
C-More Controller
(or Control Box)
A control system developed by AERCO International and currently
used in all Benchmark and KC Series product lines
EMS Energy Management System
FDX Full-Duplex
HDX Half-Duplex
Hex Hexadecimal Number (0 - 9, A - F)
I/O Box
Input/Output (I/O) Box currently used on all Benchmark and KC
Series products
LSB Least Significant Byte
Modbus®
A serial, half-duplex data transmission protocol developed by AEG
Modicon
MSB Most Significant Byte
RS232
A standard for serial, full-duplex (FDX) transmission of data based
on the RS232 Standard
RS422
A standard for serial, full-duplex (FDX) transmission of data based
on the RS422 Standard
RS485
A standard for serial, half-duplex (HDX) transmission of data
based on the RS485 Standard
RTU Remote Terminal Unit