Rockwell-automation 1769-HSC Compact High Speed Counter Module Manual de usuario descargar pdf (Pagina 28)

28 Rockwell Automation Publication 1769-UM006E-EN-P - July 2013

Chapter 2 Module Operation

Input Frequency

Maximum input frequency is determined by the input configuration as shown in

the table.

Counter Types

Each of the four possible counters can be configured to stop counting and set a

flag at its limits (linear counter) or to rollover and set a flag at its limits (ring

counter). A counter’s limits are programmed by the CtrnMaxCount and

CtrnMinCount words in the module’s configuration array. Both types are

described below.

Linear Counter

Figure 7 illustrates linear counter operation. In linear operation, the current count

(Ctr[n].CurrentCount) value remains between, or equal to, the

user-programmed minimum count (CtrnMinCount) and maximum count

(CtrnMaxCount) values. If the Ctr[n].CurrentCount value goes above (>) or

below (<) these values, the counter stops counting, and an overflow/underflow

bit is set. The overflow/underflow bits can be reset using the

CtrnResetCounterOverflow and CtrnResetCounterUnderflow bits.

Figure 7 - Linear Counter Diagram

Pulses are not accumulated in an overflow/underflow state. The counter begins

counting again when pulses are applied in the proper direction. For example, if

you exceed the maximum by 1000 counts, you do not need to apply 1000 counts

in the opposite direction before the counter begins counting down. The first

pulse in the opposite direction decrements the counter.

Input Configuration Input Frequency

1769-HSC Module

Input Frequency

Packaged Controller

X4 Quadrature encoder 250 kHz 250 kHz

X2 Quadrature encoder 500 kHz 250 kHz

All other configurations 1 MHz 250 kHz

Count Up

Count Down

Counter Value

Maximum Count Value

Overflow and Hold

Minimum Count Value

Underflow and Hold

1 2 ... 23 24 25 26 27 28 29 30 31 32 33 ... 169 170

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Rockwell-automation 1769-HSC Compact High Speed Counter Module Manual de usuario Pagina 28