Mitsubishi Electric FR-A740-00023 Instruction Manual page 337

(8) Instructions for the program
1) When data from the computer has any error, the inverter does not accept that error. Hence, in the user program,
always insert a retry program for data error.
2) All data communication, e.g. run command or monitoring, are started when the computer gives a communication
request. The inverter does not return any data without the computer's request. Hence, design the program so that
the computer gives a data read request for monitoring, etc. as required.
3) Program example
To change the operation mode to computer link operation
10 OPEN"COM1:9600,E,8,2,HD"AS #1
20 COMST1,1,1:COMST1,2,1
30 ON COM(1)GOSUB*REC
40 COM(1)ON
50 D$="01FB10002"
60 S=0
70 FOR I=1 TO LEN(D$)
80 A$=MID$(D$,I,1)
90 A=ASC(A$)
100 S=S+A
110 NEXTI
120 D$=CHR$(&H5)+D$+RIGHT$(HEX$(S),2)
130 PRINT#1,D$
140 GOTO 50
1000 *REC
1010 IF LOC(1)=0 THEN RETURN
1020 PRINT"RECEIVE DATA"
1030 PRINT INPUT$(LOC(1),#1)
1040 RETURN
General flow
Line number
10
to
40
50
to
140
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 loss etc., the inverter cannot
be stopped. When the communication check time interval has elapsed, the inverter will come to an alarm stop
(E.PUE, E.SER). 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 loss, computer fault etc., the inverter does not detect such a fault. This
should be fully noted.
: Communication file open
: Circuit control signal (RS, ER) ON/OFF setting
: Interrupt definition at data receive
: Interrupt enable
: Addition of control code and sum code
: Interrupt occurrence at data receive
Initial setting
of I/O file
Send data processing
Data setting
Sum code Interrupt
calculation
Data send
CAUTION
Communication operation and setting
Initial setting of I/O file
Send data setting
Sum code calculation
Data transmission
Interrupt data receive
1000
Receive data
processing
to
Data import
Screen display
1040
4
327