Mitsubishi Electric FR-E700 Instruction Manual page 391

Parameter
Signal loss detection (Pr. 122)
If a signal loss (communication stop) is detected between the inverter and master as a result of a signal
loss detection, a communication fault (E.PUE) occurs and the inverter trips (as set in Pr. 502).
When the setting is "9999", communication check (signal loss detection) is not made.
When the setting value is "0" (initial value), RS-485 communication can be made. However, a com-
munication fault (E.PUE) occurs as soon as the inverter is switched to the operation mode (network
operation mode in the initial setting) with the control.
A signal loss detection is made when the setting is any of "0.1 s to 999.8 s". To make a signal loss de-
tection, it is necessary to send data (refer to Mitsubishi inverter protocol control code (page 6-250),
Modbus®-RTU communication protocol (page 6-267)) 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 made from the first communication in the operation mode with control
source valid (network operation mode in the initial setting).
Example PU connector communication, Pr. 122 = 0.1–999.8s
Computer
Data flow
Inverter
Inverter
Data flow
Computer
Fig. 6-118: Signal loss detection
NOTES
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 pro-
vides 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 will come to an alarm stop (E.PUE). The inverter can be coasted to a stop by
switching 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.
FR-E700 SC EC/ENE
Operation mode External
Pr. 122
Communication
check counter
Communication operation and setting
PU
Check start
Alarm E.PUE
Time
I001220E
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