Unication Messenger m90 Manual de usuario descargar pdf (Pagina 159)

Ladder

151

System Bit

The result instruction can be to an external output device (for example: alarm bell) or to an

internal system element (for example: SB 80 activate linearization).

During the system scan, the processor evaluates all of the program elements on the Ladder

net before the Inverted Coil for power flow continuity.

If no power flow continuity exists in the net: the Inverted Coil address instruction is ON

(logic 1).

If power flow continuity exists in the net: the Inverted Coil address is OFF (logic 0).

Set Coil

A set coil separates the coil from the action or condition that energized the coil. Once

energized, a set coil's result is no longer dependant on the action that energized it. A set

coil stays energized (latched) until its condition is reset (unlatched) by a reset coil.

A set coil can be:

Memory Bit

System Bit

Output

An example of a set coil is an overhead light. When we turn on a light it stays lit until we

turn it off (reset or unlatch it) or the light bulb burns out. Luckily, you do not have to hold the

light switch to keep the light on.

An example of a coil that you do not want to be set (latched) is a car horn. You expect it to

toot only when you press on the horn button and you expect it to stop when you stop

pressing on the horn button.

Use set and reset coils to preserve a condition in a program.

Reset Coil

A reset coil turns off (unlatches) a set coil, provided that there is logic continuity to the reset

coil. Once a set coil is energized it stays energized, independent of the original set

condition, until a reset coil with the same address resets (unlatches) the coil condition.

A reset coil can be:

Memory Bit

System Bit

Output

Do not use a set coil without a reset coil in a program.

Timers (T)

U90 Ladder offers 64 On Delay Timers. Timers have a preset value, a current value, and a

bit value. Timers always count down from the Preset Value.

Click on the Timers folder in the Program Navigation pane to display the complete list of

Timers. Scroll down to view the complete list.

1 2 ... 154 155 156 157 158 159 160 161 162 163 164 ... 406 407

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Unication Messenger m90 Manual de usuario Pagina 159