Mitsubishi Electric 800 Series Instruction Manual page 502

 Communication specifications
• The communication specifications are given below.
Item
Communication protocol
Conforming standard
Connectable units
Communication Speed
Control procedure
Communication method
Communication Character system
specifications
Start bit
Stop bit length
Parity check
Error check
Terminator
Waiting time setting
 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 Interchange) 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.
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
Binary (fixed at 8 bits)
1 bit
Select from the following three types:
No parity check, stop bit length 1 bit/2 bits (depends on the setting of Pr.333)
Odd parity check, stop bit length 1 bit
Even parity check, stop bit length 1 bit
CRC code check
Not used
Not used
Description
5.12 (N) Operation via communication and its settings
3
Related
parameter
4
Pr.549
―
Pr.331
Pr.332 5
―
―
5
―
―
Pr.333
Pr.334
5
―
6
―
―
7
8
9
10
501
5. PARAMETERS