Mitsubishi Electronics FX1S manual Programming Examples, Simple STL Flow

FX Series Programmable Controllers STL Programming 3

3.11Programming Examples

3.11.1A Simple STL Flow

FX1S FX1N FX2N FX2NC

Loading hopper

Y12 Y10

Start button

X0

Y11

Ore truck

Y13

X2X1

Ore dischange point

This simple example is an excerpt from a semi-automatic loading-unloading ore truck program. This example program has a built in, initialization routine which occurs only when the PLC is powered from OFF to ON. This is achieved by using the special auxiliary relay M8002.

This activates a Zone ReSeT (ZRST is applied instruction 40) instruction which ensures all of the operational STL states within the program are reset. The program example opposite shows an M8002/ZRST example.

M8002

ZRST S21 S25

The push button X0 acts as a start button and a mode selection button. The STL state S0 is initialized with the ZRST instruction. The system waits until inputs X0 and X2 are given and Y 13 is not active. In the scenario this means the ore truck is positioned at the ore discharge point, i.e. above the position sensor X2. The ore truck is not currently discharging its load, i.e. the signal to open the trucks unloading doors (Y13) is not active and the start button (X0) has been given. Once all of the points have been met the program steps on to state S21.

On this state the ore cart is moved (Y10) and positioned (X1) at the loading hopper. If the start button (X0) is pressed during this stage the ore cart will be set into a repeat mode (M2 is reset) where the ore truck is immediately returned to the loading hopper after discharging its current load. This repeat mode must be selected on every return to the loading station.

Once at the loading point the program steps onto state S22. This state opens the hoppers doors (Y11) and fills the truck with ore. After a timed duration, state S23 is activated and the truck returns (Y12) to the discharge point (X2).

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