Honeywell FMC2000 - Message Frame;Communication Procedure

FMC2000 User’s Guide
information. The server IP and TCP port must be properly
configured on FMC2000 controller. It is also necessary to
configure the IP settings for the FMC2000 controller. After
configuration, the FMC2000 tries to connect to the specified
server.
The FMC2000 does not check the “ClientID” (the first byte in
the request message; refer to the section below) in the ModBus
RTU message. However, the FMC2000 replies to a message
with its “ClientID.”
32.3 Message Frame/Communication
Procedure
Note: The FMC2000 supports Function Code 0x03 only.
0x03 : Read Holding Registers
The Requesting Message:
Device
Address
Function
Code
Starting
Address
high byte
Starting
Address
low byte
Quantity of
Registers
high byte
Quantity of
Registers
low byte
CRC
low byte
CRC
high
byte
Client
ID
0x03
addr
addr
qty
qty
crc
crc
Note: The max Quantity value is 48.
The Answering Message:
Device
Address
Function
Code
Byte Count
Register Values
CRC
low byte
CRC
high byte
Client
ID
0x03
len
MSB……LSB
crc
crc
102