IDEC MicroSmart - Manual (Page 502)

29: T ROUBLESHOOTING
29-22 « FC4A M ICRO S MART U SER ’ S M ANUAL »
Restriction on Ladder Programming
Due to the structure of WindLDR , the following ladder diagram cannot be programmed — a closed circuit block is formed
by vertical lines, except for right and left power rails, and the closed circuit block contains one or more prohibited instruc-
tions shown in the table below.
The error detection depends on the version of WindLDR . When using WindLDR ver. 4.4 or earlier, particular care is needed.
Modifying Prohibited Ladder Programs
Intended operation can be performed by modifying the prohibited ladder program as shown in the examples below:
Prohibited Instructions OUT, OUTN, SET, RST, TML, TIM, TMH, TMS, CNT, CDP, CUD, SFR, SFRN, SOTU, SOTD
Error
Detection
WindLDR
Ver. 4.4 or earlier
The ladder program is conver ted to incorrect mnemonics, without showing an error
message. The program can be downloaded to the CPU module, causing an unexpected
operation and possible danger.
WindLDR
Ver. 4.5 or later
When conver ting the ladder program, an error message is shown, such as “TIM fol-
lows an invalid operand.” Conversion fails to create mnemonics and the program is
not downloaded to the CPU module.
Caution
• When using
WindLDR ver. 4.4 or earlier, the restriction on ladder programming may cause an
unexpected operation and possible danger.
•
WindLDR ver. 4.5 or later prevents conversion of prohibited ladder program, making sure of safety.
Prohibited
Instruction
Relay 1
Program
Relay 2
Closed Circuit Block
Ver tical
Line A Ver tical
Line B
Program
Left Power Rail Right Power Rail
M0
Prohibited Ladder Program 1
TIM
100 T0
Q0 M1
M2
M0
Modified Ladder Program 1
TIM
100 T0
M1
T0 M0 Q0
M2
M0
Prohibited Ladder Program 2
TIM
100 T0
Q0 M1
M2
M0
Modified Ladder Program 2
TIM
100 T0
M1
T0 Q0
TIM
50 T1 TIM
50 T1
M2
T1