388
Special Instructions
Section 5-28
The program sections marked by dashed lines in the following diagram can be
written according to the needs of the particular program application. The pro-
cessing programming section triggered by CY is optional and can be used any
instructions but LD and LD NOT. The logic diagnostic instructions and execu-
tion condition can consist of any combination of NC or NO conditions desired.
When the execution condition is OFF, FPD(––) is not executed. When the exe-
cution condition is ON, FPD(––) monitors the time until the logic diagnostics
condition goes ON, turning ON the diagnostic output. If this time exceeds T,
the following will occur:
1,2,3...
1.
An FAL(06) error is generated with the FAL number specified in the first two
digits of C. If 00 is specified, however, an error will not be generated.
2.
The logic diagnostic instructions are searched for the first OFF input con-
dition and this condition’s bit address is output to the destination words be-
ginning at D.
3.
The CY Flag (SR 25504) is turned ON. An error processing program sec-
tion can be executed using the CY Flag if desired.
4.
If bit 15 of C is ON, a preset message with up to 8 ASCII characters will be
displayed on the Peripheral Device along with the bit address mentioned
in step 2.
Control Data
The function of the control data bits in C are shown in the following diagram.
Logic Diagnostic
Instructions
If the time until the logic diagnostics condition goes ON exceeds T, the logic
diagnostic instructions are searched for the OFF input condition. If more than
one input condition is OFF, the input condition on the highest instruction line
and nearest the left bus bar is selected.
When IR 00000 to IR 00003 are ON, the normally closed condition IR 00002
would be found as the cause of the diagnostic output not turning ON.
SR 25504
(CY Flag)
FPD(
−−
)(50)
T
C
D
Processing after
error detection.
Execution
condition
Branch
Logic
diagnostic
instructions
Diagnostic
output
15 14 08 07 00
FAL number
(2-digit BCD, 00 to 99)
C:
Not used. Set to zero.
Diagnostics output
0 (OFF): Bit address output (binary)
1 (ON): Bit address and message output (ASCII)
00000
00002
00001
00003
Diagnostic
output
