Automating Manufacturing Systems - Process Control and ...

plc function ref - 34.5
OSR, OSF - One Shot Rising, One Shot Falling
A
OSR
ONE SHOT RISING
Storage Bit B3:4/5
Output Bit 2
Output Word O:001
Description:
This instruction will convert a single positive edge and convert it to a bit
that is on for only one scan. When ’A’ goes from false to true a positive
(or rising) edge occurs, and bit ’O:001/2’ will be on for one scan. Bit
’B3:4/5’ is used to track the state of the input to the function, and it can
be considered equivalent to an enable bit.
The OSF function is similar to the OSR function, except it is triggered on a
negative edge where the input falls from true to false.
Status Bits: none
Registers: none
Available on: Micrologix, PLC-5
TND - Temporary eND
A
TND
Description:
When ’A’ is true this statement will cause the PLC to stop examining the
ladder logic program, as if it has encountered the normal end-of-program
statement.
Status Bits: none
Registers: none
Available on: Micrologix, PLC-5
34.1.3 Timers and Counters
Counter memory instructions can share the same memory location, so some redundant
bits are mentioned here.