(N) Operation via communication and its settings
PARAMETERS
593
5
GROUP
N
Signal loss detection (Pr.539 Modbus-RTU communication check time
interval)
• If a signal loss (communication) is detected between the inverter and the master as a result of a signal loss detection, an
inverter communication fault (E.SER) occurs and the inverter trips.
• When the setting is "9999", communication check (signal loss detection) is not made.
• When the setting is "0", reading, etc. of monitors and parameters is possible, though a Communication fault (inverter)
(E.SER) occurs instantly when the Network operation mode is switched to.
• A signal loss detection is made when the setting is any of "0.1 s to 999.8 s". To make a signal loss detection, it is necessary
to send data from the master within the communication check time interval. (The inverter makes a communication check
(clearing of communication check counter) regardless of the station number setting of the data sent from the master).
• The communication check is made from the first communication in the Network operation mode (can be changed by Pr.551
PU mode operation command source selection).
• The communication check time by query communication includes a no data time (3.5 bytes).
This no data time differs according to the communication speed, so take this time no data time into consideration when
setting the communication check time.
NOTE
• For the RS-485 terminal communication, the operation at a communication error occurrence depends on the Pr.502 Stop
mode selection at communication error setting. (Refer to page 560)
Operation mode
Example: RS-485 terminal communication, Pr. 539 = "0.1 to 999.8 s"
External NET
Check start
Time
Inverter (slave)
Inverter (slave)
Communication
check counter
Pr.539
PLC (master)
PLC (master)
Query Message1 Query Message2
Data absence time
(3.5 bytes or more)
Response Message1
Response Message2
Fault
(E.SER)
Operation mode External NET
Check start
Time
Inverter (slave)
Inverter (slave)
Communication
check counter
Pr.539
PLC (master)
PLC (master)
Query Message2
Fault
(E.SER)
Data absence time
(3.5 bytes or more)
Query Message1
Query communication
Broadcast communication
ONOFF
ALM
ONOFF
ALM
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