TIA Portal Clock Memory and System Memory

1. Clock Memory and System Memory Activation in TIA Portal

Clock Memory by default is DEACTIVATED. To activate it highlight your PLC and go to: Properties » General » System and clock memory » Clock memory bits and System memory bits:

2. Clock Memory Bits in TIA Portal – Description

Each memory bit is set on and off with described frequency.

Frequency Wikipedia

• 0.5 Hz:
• 0.625 Hz:
• 1 Hz:
• 1.25 Hz:
• 2 Hz:
• 2.5 Hz:
• 5 Hz:
• 10 Hz:
  

  3.  System memory byte in TIA Portal – description

Since we’re on the ‘System and clock memory’ settings page I think it’s worth while to also have a look at system memory bits:

These are also some really helpful bits.

• You can use the first scan bits for example to set some values once on the first scan (after PLC startup).
• Always FALSE is good for “commenting out” parts of ladder logic that you do not wish to use int the program at the moment but might have use for it later on during commissioning/ next phases. etc.
• Always TRUE is useful for bypassing signals (that you can’t force) during software debugging.