Mitsubishi Electric FR-CC2-N Series Instruction Manual page 121

NOTE
• To use the MODBUS RTU protocol, set "1" in Pr.549 Protocol selection.
• If MODBUS RTU communication is performed from the master to the address 0 (station number 0), the data is broadcasted,
and the converter unit does not send any reply to the master. To obtain replies from the converter unit, set Pr.331 RS-485
communication station number ≠ "0 (initial value)".
• Some functions are disabled in broadcast communication. (Refer to
 Communication specifications
• The communication specifications are shown in the following table.
Item
Communication protocol
Conforming standard
Number of connectable units
Communication speed
Control procedure
Communication method
Character
system
Start bit
Stop bit length
Communication
specifications
Parity check
Error check
Terminator
Time delay 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 converter unit, or check the converter unit's operating status,
for example. This product classifies the data of each converter unit into holding register area (register address 40001 to
49999). The master can communicate with converter units (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.
120
5. PARAMETERS
5.7 (N) Communication operation parameters
MODBUS RTU protocol
EIA-485 (RS-485)
1: N (maximum 32 units), the setting range of station number is 0 to 247.
Selected among 300/600/1200/2400/4800/9600/19200/38400/57600/76800/
115200 bps
Asynchronous method
Half-duplex system
Binary (fixed at 8 bits)
1 bit
Select from the following three types:
No parity check, stop bit length 2 bits
Odd parity check, stop bit length 1 bit
Even parity check, stop bit length 1 bit
CRC code check
Not available
Not available
page 122.)
Description Related parameter
Pr.549
—
Pr.331
Pr.332
—
—
—
—
Pr.334
—
—
—