Sentek LMC-J-0040-1 Manual do Utilizador descarregar pdf (Página 29)

IMJ00503 V3E.DOC Page 29 of 40 19.02.2009

5. LMC-J-0050-3 Operation

6.1 Measuring Modes

The various measuring modes are distinguished by the algorithms they use for

calculation. The LMC J 0050 3 relies on the phase comparison method for normal

operation.

In order to obtain a precise measured value, the user should perform an appropriate number of

single distance shots at different frequencies of a fixed number. For DW mode and DX mode,

the number of frequencies and/or the number of single distance shots is limited, which allows

for higher measurement frequencies. On the other hand, this also places tighter demands on the

quality of operating conditions, for example, targets should be strongly reflecting. The resulting

limitations should be taken into account by the user in practical work.

In DT mode or DM mode, the user may define his/her own limits for the maximum time which

measurement is to last, by setting appropriate measuring time values in Measuring Time.

6.1.1 DM: Single Distance Measurement

In DM mode, a single distance shot is triggered. A desired measuring time can be set in the

Master’s configuring tool, using the Encoder profile and Class 2 encoder functionality.

6.1.2 DT: Distance Tracking

DT mode can be chosen for distance measurement of different kinds of surfaces (varying

reflectance). This may cause longer measuring times in the case of poor reflectance or sudden

jumps in distance. The minimum measuring time is 160 msec, the maximum time is 6 sec. On

expiry of six seconds, measurement will be aborted with an error message. A desired Measuring

Time can be set in the Master’s configuring tool, using the Encoder profile and Class 2 encoder

functionality.

6.1.3 DW: Distance Tracking With White Target (10 Hz)

DW mode uses a steady measuring rate of 10 Hz. A white target board is a necessary

prerequisite for measured values to be stable. There must be no sharp jumps in distance above

a value of 16 cm within the area being measured.

6.1.4 DX: Distance Tracking With Cooperative Target (50 Hz)

DX mode uses a steady measuring rate of 50 Hz. It is primarily intended for applications where

there is uniform carrier motion up to a rate of 4 m p. sec. The high measuring rate of 50 Hz is

achieved by involving previously measured values in calculation of a currently measured value.

Distance jumps greater than 16 cm should be avoided.

A white target board is a necessary prerequisite for stable distance readings.

6.1.5 DF: Distance Measurement with External Trigger

In D F mode, measurement begins on arrival of an external trigger pulse. This trigger pulse

releases a single distance shot.

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