Mitsubishi Electric FR-D720-0.2K-G, Инструкция по эксплуатации

Страница: 207 / 302

204
Communication operation and setting
(1) Communication specification
 The communication specifications are given below.
(2) Outline
The MODBUS protocol is the communication protocol developed by Modicon for PLC.
The MODBUS protocol performs serial communication between the master and slave using the dedicated message frame.
The dedicated message frame has the functions that can perform data read and write. Using the functions, you can read
and write the parameter values from the drive unit, write the input command of the drive unit, and check the operating
status. In this product, the drive unit data are classified in the holding register area (register addresses 40001 to 49999). By
accessing the assigned holding register address, the master can communicate with the drive unit which is a slave.
NOTE
 When "1" (MODBUS RTU protocol) is set in Pr. 549 and "384" (38400bps) in Pr. 118 , parameter unit (FR-PU07) is
disabled. When using the parameter unit (FR-PU07), change parameter using the operation panel.
 If a communication error caused by noises occurs while "2" is set in Pr. 502 , the inverter operation may restart after
the deceleration stop operation.
REMARKS
 Set Pr. 549 Protocol selection to "1" to use the MODBUS RTU protocol.
 When PU connector is selected as NET mode operation source (when Pr. 551 PU mode operation command source selection

"2"),
MODBUS RTU communication operation can be performed. (Refer to page 177.)
Parameters referred to
Pr. 502 Stop mode selection at communication error Refer to page 185
.
Pr. 779 Operation speed during communication error
Refer to page 185 .
Item Description
Related
Parameter
Communication protocol MODBUS RTU protocol Pr. 549
Conforming standard EIA-485(RS-485) —
Number of connectable devices 1:N (maximum 32 units), setting is 0 to 247 stations Pr. 117
Communication speed Selected among 4800/9600/19200 and 38400bps Pr. 118
Control procedure Asynchronous —
Communication method Half-duplex —
Communication
Character system Binary (always 8 bits) —
Start bit 1 bit —
Stop bit length
Select from the following three types
 No parity, stop bit length 2 bits
 No odd parity, stop bit length 1 bit
 Even parity, stop bit length 1 bit
Pr. 120
Parity check
Error check CRC code check —
Terminator Not used —
Waiting time setting Not used —
REMARKS
There are two different serial transmission modes: ASCII (American Standard Code for Information Interchange) mode and RTU
(Remote Terminal Unit) mode. This product supports only the RTU mode in which 1-byte (8-bit) data is transmitted as it is.
Only the communication protocol is defined by the MODBUS protocol, and the physical layer is not stipulated.