N700 Operating Instructions and Parts Manual
13. Communication function
142
(3) Communication
order
The flow of the communication protocol between an external control device and an inverter is
shown below in the time diagram.
Fig. 13- 3 Communication order
Frame start :
Frame start is recognized by signal line data transmitted.
Frame completion:
Frame completion is recognized by no data during correspond 4, 5-
character time.
Frame 1:
Transmit from external controller to inverter.
Frame 2:
Indication reflects from inverter to external controller.
Frame 2 in inverter displays as the signal that inverter receiving Frame 1 and
recognizes a suitable frame and responds, and don’t output actively.
13.2
Communication protocol
ModBus protocol that applies Query-Response Cycle method is used in the communication.
The communication network is controlled by the master equipment, and it is operated by the
method that the slave equipment reply from the transmission request of the master equipment.
ModBUS communication frame type and form is as follows.
13.2.1
Inverter read frame
It requires 1~8 parameters of Inverter.
(1) External controller transmit frame
Communication
number
Command Parameter
Parameter
count
CRC Hi
CRC Lo
Clause
Description
Data size
Specifications
Communication number
Inverter communication number
1 byte
1~32
Command
Frame type
1 byte
0x03
Parameter Parameter
2
byte
1st byte : Group
2nd byte : index
Parameter number
Request parameter
Number
2 byte
1st byte : 0x00
2nd byte : N(0x01~0x08)
CRC Hi
-
1 byte
Higher 8bit of 16 bit CRC
CRC Lo
-
1 byte
Lower 8bit of 16 bit CRC
Table 13- 4 External controller transmit frame
Frame 1
Frame 2
External control
Devices
Inverter
Waiting time
(setting with operator)