Mitsubishi Electric FR-A700 Technical Manual page 415

(6) Retry count setting [Pr. 121, 335]
Set the permissible number of retries at data
receive error occurrence. (Refer to page 448 for data
receive error for retry)
When data receive errors occur consecutively and
exceed the permissible number of retries set, an
inverter trip (E.PUE) may occur and stops the motor.
When 9999 is set, an inverter fault is not provided
even if data receive error occurs but an alarm output
signal (LF) is output.
For the terminal used for the LF signal output,
assign the function by setting 98 (positive logic) or
198 (negative logic) in any of [Pr. 190 to Pr. 196 Output
terminal function selection].
Example: PU connector communication, [Pr. 121 = 1] (initial value)
Operation mode
Computer
Wrong
Inverter
Inverter
Computer
Reception error
Example: PU connector communication, [Pr. 121 = 9999]
Operation mode
Computer
Wrong
Inverter
Inverter
Computer
Reception error
LF OFF
Always set the communication check time interval before starting operation to prevent hazardous conditions.
Data communication is not started automatically but is made only once when the computer provides a
communication request. If communication is disabled during operation due to signal cable breakage etc., the
inverter cannot be stopped. When the communication check time interval has elapsed, the inverter trips
(E.PUE).
The inverter can be coasted to a stop by turning ON its RES signal or by switching power OFF.
If communication is broken due to signal cable breakage, computer fault, etc, the inverter does not detect
such a fault. This should be fully noted.
Alarm (E.PUE)
Wrong
Reception error
Wrong Normal
Reception error
ON OFF
CAUTION
449
(7) Signal loss detection (RS-485
communication check time interval)
[Pr. 122, 336]
If a signal loss (communication stop) is detected
between the inverter and computer as a result of a
signal loss detection, a communication fault (PU
connector communication: E.PUE, RS-485 terminal
communication: E.SER) occurs and the inverter trips.
A signal loss detection is made when the setting is
any of 0.1 to 999.8s. To make a signal loss detection,
it is necessary to send data (control code: refer to
page 447) from
communication check time interval. (The inverter
makes communication
communication check counter) regardless of the
station number setting of the data sent from the
master).
Communication check is
communication in the operation mode having the
operation source (PU operation mode for PU
connector communication in the default setting or
network operation mode for RS-485 terminal
communication).
When the setting is 9999, communication check
(signal loss detection) is not made. If communication
is broken due to signal cable breakage, computer
fault etc., the inverter does not detect such a fault.
This should be fully noted. It is recommended to set
the communication check time interval before starting
operation to prevent hazardous conditions.
When the setting
communication from the PU connector cannot be
performed. For communication via the RS-485
terminals, monitor, parameter read, etc. can be
performed, but a communication error (E.SER)
occurs as soon as the inverter is switched to the
network operation mode.
When the setting is 0 (initial value) in
communication from RS-485 can be performed,
however, communication error (E.PUE) would occur
if switched to another operation mode with command
source (NET mode at initial setting).
Example: PU connector communication, [Pr. 122 = 0.1 to 999.8s]
Operation mode
External
Computer
Inverter
Inverter
Computer
Pr. 122
Communication
check counter
PARAMETER
the computer within the
check (clearing
started at the first
is 0 in
A700 F700
E700 D700
Alarm (E.PUE)
Check start
Time
of
2
,
,