Message Frame/Communication Procedure - Honeywell FMC2000 User Manual

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 Function
Address Code
Client 0x03
ID
Note: The max Quantity value is 48.
The Answering Message:
Device Function
Address Code
Client 0x03
ID
FMC2000 User's Guide
Starting Starting
Address Address
high byte low byte
addr addr
Byte Count
len
Quantity of Quantity of
Registers Registers
high byte low byte
qty qty
Register Values
MSB......LSB crc
102
CRC CRC
low byte high
byte
crc crc
CRC CRC
low byte high byte
crc