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8 PARAMETER FUNCTIONS
8-37
8
NOTICE
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
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
Description
Computer sending
data
The computer gives a communication request to the drive unit in accordance
with the user program
Drive unit returning
data
In response to the communication request from the computer, the drive unit
returns data to the computer.
Computer replying
data
The computer replies to the drive unit whether it could receive the drive unit
returning data properly or not.
Communication protocol in write mode (when drive unit writes data)
12ms
Drive unit
Drive unit
Computer
Computer
12ms or more
Time
Computer
sending data
returning data
Drive unit
Computer
sending data
Waiting time
MEMO
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) 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)
12ms
Drive unit
Drive unit
Time
Computer
Waiting time
12ms or more 12ms or more
Computer
sending data
Computer
returning data
Drive unit
Computer
replying data sending data
Computer
MEMO
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 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.
Approximately 12ms plus waiting time after the drive unit has completed receiving the data sent by
the computer, the drive unit sends the drive unit returning data to the computer.
Set the waiting time in Pr. 123 to match the answerable time of the computer.
MEMO
The waiting time may also be set using the computer sending data. In this case, set
9999 in Pr. 123.
NOTICE
Always allow for more than 12ms to pass after sending or receiving a message
before initiating another send message from the computer.