Rockwell-automation 1746-HSCE2 Multi-Channel High Speed Counter Module Manual de usuario descargar pdf (Pagina 28)

Publication 1746-UM002B-EN-P - August 2004

2-8 Module Operation

Gate and Preset Limitations

Because only the Z inputs are used for external gating and presetting,

the only gate/preset modes available for Counters 3 and 4 are No

Preset and Soft Preset Only. All six modes are always available for

Counters 1 and 2.

Gate and Preset Considerations

Z-pulse Preset Operation

In applications where the Z pulse of the encoder is being used to

preset the position, and where the Z pulse of the encoder is aligned

with either the A or B pulses, the capture or count value may be

affected by ± 1 count. If the Z pulse is edge aligned with the A pulse,

preset operations may not be performed accurately in any of the

quadrature modes. If the Z pulse is edge aligned with the B pulse,

preset operation may not be performed accurately in the X4

quadrature mode only. A small capacitor (for example, 0.01 µF) across

the Z inputs will dis-align these inputs and should correct this

condition.

Summary of Available

Counter Configurations

The table below summarizes the input configurations and gate/preset

modes available for all counters, based on operating mode.

IMPORTANT

In Class 1, Operating Mode 2, Counter 2 does not

have a capture value available. In Class 1, Operating

Mode 3, no capture values are available.

Operating

Mode

Counter Input Configuration Gate/Preset Mode

11All All

2All All

21All All

2 Pulse/Internal Direction All

3 Pulse/Internal Direction No Preset or Soft Preset Only

3 1 Pulse/Internal Direction All

2 Pulse/Internal Direction All

3 Pulse/Internal Direction No Preset or Soft Preset Only

4 Pulse/Internal Direction No Preset or Soft Preset Only

1 2 ... 23 24 25 26 27 28 29 30 31 32 33 ... 139 140

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Rockwell-automation 1746-HSCE2 Multi-Channel High Speed Counter Module Manual de usuario Pagina 28