Mitsubishi Electric FR-A700 Series, Technical Manual

Page: 415 / 550

449
PARAMETER
2
P
ARAM
ETE
R
(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 ].
(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 the computer within the
communication check time interval. (The inverter
makes communication check (clearing of
communication check counter) regardless of the
station number setting of the data sent from the
master).
Communication check is started at the first
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 is 0 in
,
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).
Computer
Operation mode
Reception error Reception error
Alarm (E.PUE)
Inverter
Inverter
Computer
ENQ
ACK NAK NAK
Computer
Operation mode
LF OFF OFF
Reception error Reception error
Inverter
Inverter
Computer
ENQ
ACK NAK NAK
ON
Wrong
Wrong
ENQ
ACK
Normal
ENQ
Wrong
ENQ
Wrong
Example: PU connector communication, [
Pr. 121
= 1] (initial value)
Example: PU connector communication, [
Pr. 121
= 9999]
A700 F700
E700 D700
27
Time
'03
Computer
Operation mode
Alarm (E.PUE)
Inverter
Inverter
Computer
Example: PU connector communication, [
Pr. 122
= 0.1 to 999.8s]
External
Check start
Communication
check counter
Pr. 122
CAUTION
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.