Mitsubishi Electric FR-A820-00046 Instruction Manual page 858

(N) Operation via communication and its settings
Communication specifications
● The communication specifications are given below.
Item
Communication protocol
Conforming standard
Connectable units
Communication Speed
Control procedure
Communication method
Communica-
tion specifica-
tions
Waiting time setting
Tab. 5-286: Communication specifications
Outline
● The Modbus® communication protocol was developed by Modicon for programmable controllers.
● The Modbus® protocol uses exclusive message frames to perform serial communication between
a master and slaves. These exclusive message frames are provided with a feature called "functions"
that allows data to be read or written. These functions can be used to read or write parameters
from the inverter, write input commands to the inverter or check the inverter's operating status,
for example. This product classifies the data of each inverter into holding register area (register
address 40001 to 49999). The master can communicate with inverters (for instance,. slaves) by
accessing pre-assigned holding register addresses.
NOTE There are two serial transmission modes, the ASCII (American Standard Code for Information Inter-
change) mode and the RTU (Remote Terminal Unit) mode. However, this product supports only
the RTU mode, which transfers 1 byte data (8 bits) as it is. Also, only communication protocol is
defined by the Modbus® protocol. Physical layers are not stipulated.
Message format
Programmable controller
Programmable controller
Fig. 5-324:
5 - 656
Description
Modbus® RTU protocol
EIA-485 (RS-485)
1:N (maximum 32 units), setting is 0 to 247 stations
Selected among 300/600/1200/2400/4800/9600/19200/38400/57600/
76800/115200 bps
Asynchronous system
Half-duplex system
Character
Binary (fixed at 8 bits)
system
Start bit 1 bit
Select from the following three types:
Stop bit length
No parity check, stop bit length 2 bits
Odd parity check, stop bit length 1 bit
Parity check
Even parity check, stop bit length 1 bit
Error check CRC code check
Terminator Not used
Not used
Query communication
Query Message
(Master)
Inverter (slave)
Broadcast communication
Query Message
(Master)
Inverter (slave)
Message format
Inverter response time
(Refer to the following table for the data
check time)
Response Message
Data absence time
(3.5 bytes or more)
No Response
Parameters
Related
parameter
Pr. 549
⎯
Pr. 331
Pr. 332
⎯
⎯
⎯
⎯
Pr. 334
⎯
⎯
⎯
I001227E