Rockwell-automation 1769-HSC Compact High Speed Counter Module Manual de usuario descargar pdf (Pagina 30)

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

Chapter 2 Module Operation

Counter Enable/Disable

The counter can be enabled or disabled using the CtrnEn control bit. Be aware

that disabling the counter does not inhibit any current count loading functions

(for example, preset or direct write) or any Z function.

Z Input Functions

There are three Z input functions: store, gate, and Z preset.

Store

The Z-input can be used to capture the current count value even when the

counter is counting at full 1 MHz speed.

Gate

The Z-inputs can be used to gate (hold) the counter at its current value regardless

of incoming A or B inputs. A gating function is typically one that lets pulses reach

the counter (gate open) or not (gate closed).

Z Preset

Preset can be programmed to occur based on the actions of the Z-input signal.

Inhibit and Invert

The Z-input signals can be inverted and/or inhibited, depending on the user

configuration of the CtrnZInvert and CtrnZInhibit output control bits. If the

signal is inhibited, the invert bit is the Z signal for the actions described above.

For an explanation of those bits, see

Z Inv - Z Invert (CtrnZInvert) on page 93

and

Z Inh - Z Inhibit (CtrnZInhibit) on page 93.

Direct Write

You can arbitrarily change the current count value (Ctr[n].CurrentCount) to the

direct write control value (Range12To15[n].HiLimOrDirWr). This ability

applies to ranges 12…15. The direct write value takes effect when the Load Direct

Write bit (Range12To15[n].LoadDirectWrite) transitions from 0 to 1.

If you attempt to preset and load direct write to a counter at the same time, only

the preset (CtrnPreset) will take effect.

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Rockwell-automation 1769-HSC Compact High Speed Counter Module Manual de usuario Pagina 30