InteliLite
NT
– AMF20/25, SW version 2.2, ©ComAp – September 2014 127
IL-NT-AMF-2.2-Reference Guide.pdf
Modbus protocol
The selection of the function of IL serial port is done via the setpoint
COMx Mode
in
Basic settings
57600 bps, 8 data bits, 1 stop bit, no parity
Transfer mode RTU
Function 3 (Read Multiply Registers)
Function 6 (Write Single Register)
Function 16 (Write Multiply Registers)
The response to an incoming message is sent with minimum 4.096 ms delay after message
reception
The complete description of Modbus communication protocol can be found in
Modbus Protocol
Reference Guide PI-MBUS-300
and
Open Modbus Specification Release 1.0
. Both documents are
available from web site at
http://www.modicon.com/openmbus/
Communication object vs. Register
All the data intended for communication has its representation as communication objects in the
controller. The communication object is represented by the n-byte array in the controller memory and
identified by the unique 16-bit communication object number. The register, according to Modbus
communication protocol, represents a two-byte data and in communication functions is referenced by
16-bit register address. Further in the description of communication functions
the communication
object number will always be used as a register address
and length of the communication object
will be expressed by number of registers.
Just one communication object can be read or written
by one communication function.
Hint:
To obtain communication object numbers it is possible to download the actual controller description
on-
line from controller or from (ail) archive and use “export data” function from LiteEdit software.
Hint:
Do not write setpoints repeatedly (e.g. power control from a PLC by repeated writing of baseload
setpoint via Modbus) The setpoints are stored in EEPROM memory, which can be overwritten up to
10
5
times without risk of damage or data loss, but it may become damaged, when the allowed number
of writing cycles is exceeded!
Communication object list
Setpoints of AMF25:
Group
Name
Value
Dimension Com. obj. Low limit
High limit Data type
Basic Settings
Gen-set Name
IL-NT
8637
Short string
Basic Settings
Nominal Power
200
kW
8276
1
5000
Unsigned 16
Basic Settings
Nomin Current
350
A
8275
1
10000
Unsigned 16
Basic Settings
CT Ratio
2000
/5A
8274
1
5000
Unsigned 16
Basic Settings
PT Ratio
1
/1
9579
0,1
500
Unsigned 16
Basic Settings
Vm PT Ratio
1
V/V
9580
0,1
500
Unsigned 16
Basic Settings
NomVolts Ph-N
231
V
8277
80
20000
Unsigned 16
Basic Settings
NomVolts Ph-Ph
400
V
11657
80
40000
Unsigned 16
Basic Settings
Nominal Freq
50
Hz
8278
45
65
Unsigned 16
Basic Settings
Gear Teeth
120
8252
0
500
Unsigned 16
Basic Settings
Nominal RPM
1500
RPM
8253
100
4000
Unsigned 16
Basic Settings
ControllerMode
OFF
8315
String list
