Mitsubishi Electric LE7-40GU, Instruction Manual, Page: 123 / 154

7 MODBUS/RTU, ASCII (SLAVE)
7.3 Communication Setting
121
7
Data exchange between the master station and the slave station
The master station reads and writes data from/to the coil and holding registers of the slave station, enabling monitoring of the
slave station and setting of parameters.
Coil (bit data)
■
Coil for Master station

Slave station
An area used to write instructions to the slave station.
■
Coil for Slave station

Master station
The execution result of the instruction is an area for writing.
Holding register (word data)
■
For monitoring by the master station
The status of the slave station monitored by the master station is stored in this area.
■
For writing to RAM in the slave station
Data to be written to the RAM in the slave station is stored in this area.
RAM writing data is reflected in the settings, but is not stored in the case of power failure.
It can be written only to LE7-40GU.
■
For writing to RAM + ROM in the slave station
An area to store data to perform the above RAM w data power failure writing.
In the ROM for storage against power interruption, the allowable number of times of writing is limited. Accordingly, data
cyclically written and updated by the PLC must be written only to the RAM.
• The numerical value of each parameter is treated as real data without a decimal point. The data defines the
minimum value and the maximum value within LE7-40GU and automatically rewrites it to the minimum
value or the maximum value when writing data outside the range. At that time, a network alarm "22" is
output to the alarm display (H00EB) of the holding register.
• For holding registers where change of password of monitor, parameter list of setting items="

", if the
password setting and the password input do not match, the holding register cannot be written to, the monitor
value of the holding register is rewritten with a numerical value of maximum value +1, and the set numerical
value can no longer be monitored.
• If an error occurs triggered by the request from the master station, the slave station turns ON the coil of the
network alarm occurrence flag (H101A), and outputs the address of the holding register that has the error to
the holding register of the device number of the network alarm (H00EC).