Beretta 20141085, Руководство по установке, Страница: 103 / 112

SYSTEM MANAGER
103
8 MODBUS CONNECTION
The thermal mode is equipped with a Modbus connection (based on
the RS485 communication standard) that supports the remote man-
agement and adjustment of the aforementioned thermal module.
The Modbus connection is available in the low-voltage terminal board.
MO1
BUS 1 SB Modbus 0-10V TA
1 2 3 4 9 10 11 5 6 7 8
A B
Configuration
The following table shows the connection details.
Protocol Modbus RTU
Slave address
Adjustable from the display.
Default: 1
Supported Modbus controls
Read Holding registers (03)
Write single holding register (06)
Write multiple holding registers
(10)
Baud rate 9600 bps.
Length 8
Parity No
Stop Bits
1 or 2 (adjustable from PB or PC
software)
Connection
RS485 (2 wires + optional
earthing)
As shown in the table above, the thermal module's address (meant
as the address of the slave device in the Modbus system) and the
number of "Stop Bits" are two adjustable values.
To modify one or the other, from the home screen, access the "Set-
tings" menu, select "General settings" and confirm.
“
Settings
”
“
General Settings
”
“
Boiler Settings
”
Access the "Other settings" menu and select "Modbus Address"
“
Other Settings
”
“
Modbus Address
”
1
“
Modbus Stopbits
”
2
“
Startup Settings
”
Registers
Depending on the type of Modbus device used to connect to the
thermal module, the registers' addressing may start from 0x0000 or
0x0001.
If addressing starts from 0x0000, the numbers of the registers listed in
the table below may be used directly for reading/writing operations; 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 value 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.
b
By sending a value other than 1 and from 16384 to register No.
99, the latter will return to the write-protected status (bit 0=0).
The table that summarises the control register's operation is provided
below:
Register
number
Access
Description Value range
L S
99 0063 X X Control register
Bit 0: enables
writing
Bit 14: controller
reset
Measurement unit selection register
Register 98 is used to change the format of the data stored in regis-
ters (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:
Register
number
Access
Description Value range
L S
98 0062 X X
Measurement
unit selection
register
Bit 0: °C/°F
Bit 1: bar/psi
Types of data
Type of data Unit
Temperature °C/°F
Voltage Volt
Pressure bar/psi
Ionisation current μA
Percentage %
Connection
RS485 (2 wires + optional
earthing)