176461 User Manual.book

MicroLogix 1500 Programmable Controllers User Manual

OSR - One Shot Rising

OSF - One Shot Falling

Instruction Type: output

Table 12-11: Execution Time for the OSR and OSF Instructions

Instruction

OSR

OSF

True

2.71 µs

1.88 µs

When Rung Is:

False

2.43 µs

3.01 µs

Use the OSR and OSF instructions to trigger an event to occur one time. These instructions trigger an event based on a change of rung state, as follows:

• Use the OSR instruction when an event must start based on the false-to-true

(rising edge) change of state of the rung.

• Use the OSF instruction when an event must start based on the true-to-false

(falling edge) change of state of the rung.

These instructions use two parameters, Storage Bit and Output Bit.

• Storage Bit - This is the bit address that remembers the rung state from the previous scan.

• Output Bit - This is the bit address which is set based on a false-to-true (OSR) or true-to-false (OSF) rung transition. The Output Bit is set for one program scan.

To re-activate the OSR, the rung must become false. To re-activate the OSF, the rung must become true.

Table 12-12: OSR Storage and Output Bit Operation

Rung State Transition

false-to-true (one scan) true-to-true true-to-false and false-to-false

Storage Bit

bit is set bit is set bit is reset

Table 12-13: OSF Storage and Output Bits Operation

Rung State Transition

true-to-false (one scan) false-to-false

Storage Bit

bit is reset bit is reset

Output Bit

bit is set bit is reset bit is reset

Output Bit

bit is set bit is reset

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Relay-Type (Bit) Instructions

Table 12-13: OSF Storage and Output Bits Operation

Rung State Transition

false-to-true and true-to-true

Storage Bit

bit is set

Output Bit

bit is reset

Addressing Modes and File Types can be used as shown in the following table:

Table 12-14: OSR and OSF Instructions Valid Addressing Modes and File Types

For definitions of the terms used in this table see “Using the Instruction Descriptions” on page 11-2.

Data Files Function Files

Address

Mode

Parameter

Address

Level

Storage Bit

Output Bit • •

• •

• • • • •

•

•

•

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MicroLogix 1500 Programmable Controllers User Manual

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