Delta DVP-ES2 Manual do Utilizador descarregar pdf (Página 171)

100

101

3. Instruction Set

3-55

API Mnemonic Function

WDT P Watchdog Timer Refresh

Controllers

ES2/EX2 SS2

SA2

SX2

OP Descriptions Program Steps

N/A

WDT, WDTP: 1 step

PULSE 16-bit 32-bit

ES2/EX2 SS2

SA2

SX2 ES2/EX2 SS2

SA2

SX2 ES2/EX2 SS2

SA2

SX2

Explanations:

1. WDT instruction can be used to reset the Watch Dog Timer. If the PLC scan time (from

address 0 to END or FEND instruction) is more than 200ms, the ERROR LED will flash. In

this case, users have to turn the power OFF and then ON to clear the fault. PLC will

determine the status of RUN/STOP according to RUN/STOP switch. If there is no

RUN/STOP switch, PLC will return to STOP status automatically.

2. Time to use WDT:

a) When an error occurs in the PLC system.

b) When the scan time of the program exceeds the WDT value in D1000. It can be modified by

using the following two methods.

i. Use WDT instruction

STEP0 END(FEND)

WDT

ii. Use the set value in D1000 (Default: 200ms) to change the time for watchdog.

Points to note:

1. When the WDT instruction is used it will operate on every program scan as long as its input

condition has been made. To force the WDT instruction to operate for only ONE scan,

users have to use the pulse (P) format of the WDT instruction, i.e. WDTP.

2. The watchdog timer has a default setting of 200ms. This time limit can be customized to

users requirement by editing the content in D1000, the wathdog timer register.

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Delta DVP-ES2 Manual do Utilizador Página 171

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