QUANTA DQ61, User Manual, Page: 18 / 22

Pag. 18
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7 Remote Control
Through the RS485 port (when the corresponding option board is installed) DQ61 can be controlled by an
External manager communicating with MODBUS protocol.
7.1.1 Communication: Physical Layer
Asynchronous serial communication, half-duplex, 19200bps (default), 8 data bit (LSB first), even parity, 1 stop-
bit.
7.1.2 Communication: Data Layer
Protocol MODBUS Slave over serial line RTU mode.
Please refer to MODBUS over serial line specification and implementation guide V1.02 of 20/12/2006 by
Modbus.ORG.
The address of the MODBUS Slave is the ID MODBUS set from the Service Menu.
The Protocol Data Unit (PDU) exchanged with the upper level are associated with the address above, and
check for error checking (CRC), forming the Application Data Unit (ADU).
7.1.3 Communication: Application Layer
MODBUS Application level second MODBUS Application Protocol Specification V1.1b of 28/12/2006 by
Modbus-IDA.ORG for the management of PDUs exchanged with the lower levels.
The application layer defines the MODBUS PDU as formed by the following fields:

Function Code
–
Function code indicates the type of action required by the Client to the Server.

Data
–
Field data concerning the operation of control or monitoring required by the Client to the Server.
Are supported only the following function codes:
Function Code Description
03 (0x03) Read Holding Registers
16 (0x10) Write Multiple Registers
As described in detail below, the table of Holding Registers contains not only all the variables that can be
monitored and modified (read-write) by the External Manager, but also the variables monitored only (Read-
Only) allocated all together in a separate address space, which in this case shall be extended to the maximum
extent permitted by MODBUS (0x0000 to 0xFFFF). Is therefore rejected each write request involving the
records Read-Only in that address space.
Typical MODBUS requests for diagnostic are not handled over serial lines (08 (0x08) Diagnostics, 11 (0x0B)
Get Comm Event Counter and 12 (0x0C) Get Comm Event Log).
7.1.4 Controllable Variables Table
The data of all controllable variables are mapped into a table of 16-bit registers, depending on the model
MODBUS data representation.
7.1.5 Data types
The data is divided into the following types:

BOOL
– binary value 0 or 1