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C0MMUNICATIONS
The protocol to be used is Modbus RTU. This is implemented by the master (PC, PLC, etc.) issuing
a poll to the slave (BurnerPRO) and the slave responding with the appropriate message.
A typical format of a poll request is as follows:
Table 1: MESSAGE FORMAT
DST refers to the logical address of the slave.
FNC is the function being requested. FNC 03 is a read request.
ADR is the message number or register number of the data being requested.
For the BurnerPRO all registers are mapped as HOLDING REGISTERS, FNC 03. Register
addresses begin at 40001 but is interpreted as address 00.
DAT is the number of words being requested. A word is an integer consisting of 2 bytes.
The normal response from a slave is as follows:
Table 2: MODBUS
DBC is the data byte count being returned. It must be two times the DAT number from the poll
request.
DATA is the data returned and is always a series of 2 byte integers. If 4 words were requested then
DBC would be 8 and there would be 8 data bytes or 4 data words containing the requested data.
The default format of the data is N,8,1 meaning no parity, and 1 stop bit. Baud rate is select-
able through the keypad / display. As shipped the baud rate is 9600.
Communication to the BurnerPRO control is made through the RJ45 port located on the side of the
control. Since the RJ45 port is not compliant with a standard network Ethernet pinout, it’s highly
recommended that an ED610 breakout board be utilized to gain physical access to the modbus com-
munication signals. The physical method for communications is RS485, half duplex. The modbus
communication signals are designated “A” or “-”and “B” or “+”. Fireye offers a Modbus connection
kit for the BurnerPRO. The kit consists of the ED610 breakout board, 6ft CAT5 Ethernet cable, and
a wall mount power supply. Fireye also offers the UC485 USB adapter for connection to a PC.
DST FNC ADR
HI
ADR
LO
DAT
HI
DAT
LO
CRC
LO
CRC
HI
DST FNC DBC DATA….
Hi/Lo
CRC
LO
CRC
HI
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