6
vacon • 28
Communications
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6.
C
OMMUNICATIONS
Features of the Modbus-Vacon interface:
•
Direct control of Vacon drive (e.g. Run, Stop, Direction, Speed reference, Fault reset)
•
Full access to all Vacon parameters
•
Monitor Vacon status (e.g. Output frequency, Output current, Fault code)
6.1
Data addresses in Modbus messages
All data addresses in Modbus messages are referenced to zero. The first occurrence of a data item
is addressed as item number zero. For example:
•
The coil known as ‘Coil 1’ in a programmable controller is addressed as ‘Coil 0000’ in the
data address field of a Modbus message.
•
Coil 127 decimal is addressed as ‘Coil 007E hex’ (126 decimal).
•
Holding register 40001 is addressed as register 0000 in the data address field of the mes-
sage. The function code field already specifies a ‘holding register’ operation. Therefore the
‘4XXXX’ reference is implicit.
•
Holding register 40108 is addressed as register 006B hex (107 decimal).
6.2
Supported Modbus Functions
The Vacon variables and fault codes as well as the parameters can be read and written from
Modbus. The parameter addresses are determined in the application. Every parameter and actual
value have been given an ID number in the application. The ID numbering of the parameter as well
as the parameter ranges and steps can be found in the application manual in question. The
parameter value must be given without decimals. If several parameters/actual values are read with
one message, the addresses of the parameters/actual values must be consecutive.
Table 13. Supported functions
Function
(dec)
Function
(hex)
Modbus Function Name
TCP/RTU
Access
type
Address
range
(hex)
1 1
Read
coils
TCP
only
Discrete
(1-bit)
00000-
0FFFF
2
2
Read Discrete Inputs
TCP only
Discrete
(1-bit)
10000-
1FFFF
3
3
Read Holding Registers
TCP&RTU
Register
(16bit)
40000-
4FFFF
4
4
Read Input Registers
TCP&RTU
Register
(16bit)
30000-
3FFFF
5
5
Write Single Coils
TCP only
Discrete
(1-bit)
00000-
0FFFF
6
6
Write Single Register
TCP&RTU
Register
(16bit)
40000-
4FFFF
Summary of Contents for 100 HVAC
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