Instruction Manual

107Publication 1753-UM001C-EN-P - March 2010 107
Chapter
12
High-Speed Counters
Introduction
This chapter covers using counters in these systems:
GuardPLC 1200 controllers
GuardPLC 1800 controllers
GuardPLC 2000 controllers using a 1755-HSC module
Counter/Decoder Modes
The counters can be used in these operating modes:
Counter mode
Decoder mode
The two counters can be used in different modes at the same time.
Counter Mode
Counter mode is used for counting pulses at speeds up to 1 MHz on
the GuardPLC 2000 controllers and 100 kHz on the GuardPLC 1200
and 1800 controllers.
Follow these guidelines when using counters in a GuardPLC system:
The 5V signal must be between 4.5V and 5.5V, while the 24V
signal must be between 13V and 26.4V.
The steepness of the falling edge must be at least 1V per μs.
The low and high signal times must be at least 5 μs for the
GuardPLC 1200 controller (duty cycle 50% at 100 kHz) and
0.5 μs for the GuardPLC 2000 controller (duty cycle 50% at
1MHz).
Shield the cable against noise.
Topic Page
Counter/Decoder Modes 107
Understand Counter Module Configuration 109