Mitsubishi FX3U Series Programming Manual page 722

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Table of Contents

Series Programmable Controllers

Programming Manual - Basic & Applied Instruction Edition

Guideline of the watchdog timer set value

A value acquired by the following procedure can be regarded as the guideline of the watchdog timer set

If an acquired value is 200 ms or less, however, it is not necessary to change the watchdog timer set value.

1) Write a program to be executed from GX Developer to the PLC.

[Online]→[Write to PLC...]

2) Set the current value of D8000 to "1000" using the device test function in GX Developer.

[Online]→[Debug]→[Device test...]→ "Word device/buffer memory" in Device test dialogbox

3) Set the PLC mode to RUN, and execute the program. (Execute this instruction also.)

4) Monitor the maximum scan time D8013 using the device batch monitoring function in GX Developer.

5) The value of D8013 is stored in every 0.1 m seconds.

Watchdog timer time should be one-tenth of the value added 50 to 100 to D8013.

• Setting WDT (FNC 07) instruction just before and after INITR instruction as shown below:

An operation error is caused in the following cases; The error flag M8067 turns ON, and the error code is

stored in D8067.

• When any device number other than the head device number of a sector of extension file registers is set to

(error code: K6706)

• When a device number to be initialized exceeds "32767" (error code: K6706)

In this case, devices up to R32767 (ER32767) are initialized.

• When the protect switch of the memory cassette is set to ON (error code: K6770)

Program example

In the program example shown below, the extension registers R0 to R2047 in the sector 0 are initialized.

Note that the extension file registers ER0 to ER2047 are also initialized if a memory cassette is attached.

• Extension registers (R) [inside the built-in RAM memory]

Device number

Current value

Before execution

33 Extension File Register Control – FNC290 to FNC299

The watchdog timer is reset.

After execution

33.3 FNC292 – INITR / Initialize R and ER

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