Spectrum-controls 1746sc-CTR4 Manuel d'utilisateur télécharger pdf (Page 47)

Chapter 5: Ladder Program Examples 47

Rate Limit Flag = 10,000Hz * 2 = 20,000Hz

Application:

Meter Proving

The 1746sc-CTR4/8 module provides a feature that allows the user to

perform meter proving functions. A typical meter proving application

would include two detector sensors that are located a fixed distance from

each other within a section of pipe used specifically for meter proving.

The operation does not disrupt the in situ flowmeter’s operation.

Detector #1

Detector #2

Displacer

Utilizing the external gate enable to start and stop count functions enables

the user to count pulses as fast as 20 microseconds to an accuracy of 1

count.

Here is an example wave form representing the start and stop transitions

on the external gate enable, and the associated pulses that the module

would accumulate:

Flow Meter Input

External Channel Enable

1 2 3 4 NA

Given the above wave form, the module will begin counting the first

positive going input pulse after the external enable input goes low. The

module will accumulate 4 counts in the channel count register and stop

when the external enable input goes high.

1 2 ... 42 43 44 45 46 47 48 49 50 51 52 ... 65 66

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Spectrum-controls 1746sc-CTR4 Manuel d'utilisateur Page 47