Modbus Connection - Riello Condexa PRO NA 75P Installation, Operation And Service Manual

SYSTEM MANAGER

MODBUS CONNECTION

8 MODBUS CONNECTION
The boiler is equipped with a Modbus connection (based on the
RS485 communication standard) that supports the remote man-
agement and adjustment of the boiler.
The Modbus connection is available on the low-voltage terminal
board.
MO1
1 2 3
0-10V TA
Configuration
The following table shows the connection details.
Protocol
Slave address
Supported Modbus con-
trols
Baud rate
Length
Parity
Stop Bits
Connection
As shown in the table above, the boiler's address (meant as the
address of the slave device in the Modbus system) and the num-
ber of "Stop Bits" are two adjustable values.
To modify one or the other, from the home screen, access the
"Settings" menu, select "General settings" and confirm.
Settings
" "
General Settings
" "
Boiler Settings
" "
Access the "Other settings" menu and select "Ind. Modbus"
Other Settings
" "
Modbus Address
" "
Modbus Stopbits
" "
Startup Settings
" "
4 5 6 7 8 9 10 11
Modbus BUS 1 SB
B A
Modbus RTU
Adjustable from the display. De-
fault: 1
Read Holding registers (03)
Write single holding register (06)
Write multiple holding registers (10)
9600 bps.
8
No
1 or 2 (adjustable from display)
RS485 (2 wires + optional ground-
ing)
1
2
Registers
Depending on the type of Modbus device used to connect to the
boiler, the registers' addressing may start from 0x0000 or 0x0001.
If addressing starts from 0x0000, the numbers of the registers list-
ed in the table below may be used directly for reading/writing op-
erations; if addressing starts from 0x0001, the numbers of registers
shown in the table, plus one, must be used for reading/writing
operations.
Control register
The control register is used for special functions.
The first one is that of enabling writing on registers. All accessible
registers, including write ones, must be first enabled to receive
data. To prevent undesired entries, it is possible to change the val-
ue in a register only during the first four seconds after the status
change of the 0 bit in the control register.
Therefore, before changing the value of a register, it is necessary to
change the status of 0 bit of the control register (register No. 99),
sending the string 1 to it.
The control register also supports the remote resetting of the
board, by changing the status of the 14 bit. Therefore, by sending
the value 16384 to register No. 99, it is possible to reset the board.
9
NOTE: By sending a value other than 1 and from 16384 to reg-
ister No. 99, the latter will return to the write-protected status
(bit 0=0).
The table below summarizes the control register's operation:
Access
Register
number
R W
99 0063 X X
Measurement unit selection register
Register 98 is used to change the format of the data stored in reg-
isters (those containing temperature or pressure values).
Before changing the value of the selection register, it is necessary
to enable it for writing by forwarding the enabling command to
the 99 control register.
The table for measurement unit selection register is the following:
Access
Register
number
R W
98 0062 X X
Types of data
Type of data
Temperature
Voltage
Pressure
Ionization current
Percentage
Connection
102
Description Value range
Bit 0: write enable
Control register Bit 14: controller
reset
Description Value range
Measurement unit Bit 0: °C/°F
selection register Bit 1: bar/psi
Unit
°C/°F
Volt
bar/psi
μA
%
RS485 (2 wires + optional
grounding)