6F3B0250
Basic Hardware and Function
229
7. Instructions
FUN 143
WDT
Watchdog timer reset
Expression
Input
-
[ WDT
n
]
-
Output
Function
When the input is ON, this instruction extend the scan time over detection time by 200 ms.
Normally, T1/T1S detects the scan time-over if a scan is not finished within 200 ms. This instruction
can be used to extend the detection time.
Execution condition
Input
Operation
Output
OFF
No execution
OFF
ON
Execution
ON
Operand
Name
Device
Register
Constant Index
X
Y
R
S
T.
C. XW YW RW SW
T
C
D
I
J
K
n
Extend time
1 - 100
Example
When R020 is ON, the scan time detection time is extended by 200 ms. The operand
n has no
effect on the extended time. It is fixed as 200 ms.
Normal detection point
Extended point
0
50
100
150
200
250
300
(ms)
Extended by 200 ms
Scan
WDT instruction
execution
Note
·
As for the upper T-series PLCs, the operand
n specifies the extended time. However in the T1/T1S,
it is fixed as 200 ms regardless of the operand
n.
CTi Automation - Phone: 800.894.0412 - Fax: 208.368.0415 - Web: www.ctiautomation.net - Email: [email protected]