Mitsubishi Electric MELIPM Series Instruction Manual page 67

Communication operation is performed in response to the
communication request from the personal computer. Therefore, if
communication is suspended due to a communication cable break
or computer failure during operation, the drive unit cannot detect a
fault and stop operation. However, operation is brought to an alarm
NOTICE
stop (E. PUE) if the time set as the communication check time
interval has elapsed.
To stop operation before the time set as the communication check
time interval is reached, reset the CPU using the RES terminal or
switch power off. The motor will then coast to a stop.
(3) Communication data and communication protocol
The following table provides the communication data and communication
protocol between the computer and drive unit.
Communication
Data
Computer sending The computer gives a communication request to the drive unit in
data accordance with the user program
Drive unit In response to the communication request from the computer, the
returning data drive unit returns data to the computer.
Computer replying The computer replies to the drive unit whether it could receive the
data drive unit returning data properly or not.
Communication protocol in write mode (when drive unit writes data)
Computer
Drive unit
Drive unit
Computer
On detection of an error at the receipt of the data sent by the
computer, the drive unit returns an error code, making the sent data
invalid. Data is retransmitted (resending of data by the computer)
MEMO
when an error occurs. Setting of Pr. 121 allows the drive unit to
come to an alarm stop if consecutive errors occur in the computer
sending data.
Communication protocol in read mode (when data is read from drive unit)
Computer
Drive unit
Drive unit
Computer
On detection of an error at the receipt of the drive unit returning
data, an error occurrence is sent using the computer replying data.
In this case, the drive unit makes retry transmission (resending of
MEMO
drive unit returning data). Setting of Pr. 121 allows the drive unit to
come to an alarm stop if consecutive errors occur in the computer
replying data.
Waiting time
Computer
sending data
12ms
Waiting time
Computer
sending data
Drive unit
returning data
12ms
8-13
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8 PARAMETER FUNCTIONS
Description
Computer
sending data
Drive unit
returning data
12ms or more
Computer
replying data
12ms or more 12ms or more
Time
Computer
sending data
Time
8