178
Communication operation and setting
[RS-485 terminal communication related parameter]
4.19.4 Communication EEPROM write selection (Pr. 342)
â‹… When changing the parameter values frequently, set "1" in Pr. 342 to write them to the RAM. The life of the EEPROM will
be shorter if parameter write is performed frequently with the setting unchanged from "0 (initial value)" (EEPROM write).
Parameter
Number
Name
Initial
Value
Setting Range Description
331
RS-485 communication station
number
0
0 to 31 (0 to 247)
*1
Set the inverter station number. (same
specifications as Pr. 117)
332 RS-485 communication speed 96
3, 6, 12, 24, 48,
96, 192, 384
Used to select the communication speed.
(same specifications as Pr. 118)
333
*2
RS-485 communication stop bit
length
1 0, 1, 10, 11
Select stop bit length and data length. (same
specifications as Pr. 119)
334
RS-485 communication parity
check selection
2 0, 1, 2
Select the parity check specifications. (same
specifications as Pr. 120)
335
*3
RS-485 communication retry
count
1 0 to 10, 9999
Set the permissible number of retries at
occurrence of a data receive error.
(same specifications as Pr. 121)
336
*3
RS-485 communication check
time interval
0s
0
RS-485 communication can be made, but the
inverter will come to an alarm stop in the NET
operation mode.
0.1 to 999.8s
Set the interval of communication check time.
(same specifications as Pr. 122)
9999 No communication check
337
*3
RS-485 communication waiting
time setting
9999
0 to 150ms,
9999
Set the waiting time between data
transmission to the inverter and response.
(same specifications as Pr. 123)
341
*3
RS-485 communication CR/LF
selection
1 0, 1, 2
Select presence/absence of CR/LF.
(same specifications as Pr. 124)
549 Protocol selection 0
0 Mitsubishi inverter (computer link) protocol
1 Modbus-RTU protocol *4
*1 When "1" (Modbus-RTU protocol) is set in Pr. 549, the setting range within parenthesis is applied.
*2 For the Modbus-RTU protocol, the data length is fixed to 8 bits and the stop bit depends on the Pr. 334 setting. (Refer to page 189)
*3 The Modbus-RTU protocol becomes invalid.
*4 The Modbus-RTU protocol is valid for only communication from the RS-485 terminals.
*5 The above parameters can be set when Pr. 160 User group read selection = "0". (Refer to page 156)
CAUTION
â‹… If communication is made without Pr. 336 RS-485 communication check time interval being changed from "0" (initial value), monitor,
parameter read, etc. can be performed, but the inverter results in an alarm as soon as it is switched to the NET operation mode.
If the operation mode at power on is the network operation mode, a communication alarm (E.SER) occurs after first
communication.
When performing operation or parameter write through communication, set "9999" or more to Pr. 336. (The setting depends on
the computer side program.) (Refer to page 183)
â‹… Always reset the inverter after making the initial settings of the parameters. After you have changed the communication-related
parameters, communication cannot be made until the inverter is reset.
Parameters written via the inverter's PU connector, RS-485 terminals, or from the communication option can be
written to the RAM. Set this parameter when frequent parameter changes are required.
Parameter
Number
Name
Initial Value
Setting
Range
Description
342
Communication EEPROM write
selection
0
0
Parameter values written by communication are
written to the EEPROM and RAM.
1
Parameter values written by communication
are written to the RAM.
The above parameters can be set when Pr. 160 User group read selection = "0". However, it can be set any time when the communication
option is connected.
(Refer to page 156)
REMARKS
â‹… When Pr. 342 is set to "1" (only RAM write), the new values of the parameters will be cleared at power supply-off of the inverter.
Therefore, the parameter values available when power is switched on again are the values stored in EEPROM previously.
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