Models FL3100/3101
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8.0 MODBUS Interface
Standard Model FL3100 or FL3101 Flame Detectors include a Single MODBUS
Communications Board that is referenced as Comm 1. A Dual MODBUS feature
is optional, which includes two independent communications channels
referenced as Comm 1 and Comm 2.
NOTE - Comm 2 is utilized as a backup communications channel, therefore it is
not recommended to have both Comm 1 and Comm 2 channels active
simultaneously. If the dual Comm option is ordered, the Analog output will not be
available.
8.1
Baud Rate
The Baud Rate is a selectable setting via the MODBUS Communications
Interface. The selectable baud rates are 19.2K, 9600, 4800, or 2400 bits per
second.
8.2
Data Format
The Data Format is a selectable setting via the MODBUS Communications
Interface. The selectable data formats are as follows:
Data Bits
Parity
Stop Bit
Format
8
None
1
8-N-1
8
Even
1
8-E-1
8
Odd
1
8-O-1
8
None
2
8-N-2
8.3 MODBUS Read Status Protocol (Query/Response)
8.3.1 MODBUS Read Query Message
Byte
MODBUS
Range
Referenced to
FL3100, FL3101
1
st
Slave Address
1-247
*
(Decimal)
FL3100, FL3101 ID
(Address)
(X = 0 or 1 Model
Type)
2
nd
Function Code
03
Read Holding
Registers
3
rd
Starting Address
Hi
**
00
Not Used by FL3100,
FL3101
4
th
Starting Address
Lo
**
00-FF (Hex)
FL3100, FL3101
Commands
5
th
No. of Registers Hi
00
Not Used by FL3100,
FL3101
6
th
No. of Registers Lo
01
No. of 16 Bit Registers
7
th
CRC Lo
00-FF (Hex)
CRC Lo Byte
8
th
CRC Hi
00-FF (Hex)
CRC Hi Byte