Pfeiffer Vacuum QMG 422 Operating Instructions Manual Download Page 49

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BG 805 981 BE (0201) QMG422.oi

With

cycle-MODE

choose single channel

(MONO)

or multichannel

(MULTI)

mode

The measurement cycle is started and stopped with

run/halt

and its state is

indicated with the

mono, multi

and

halt

LEDs.

The number of measurement cycles is chosen with

cycle-CYCLES:

1...10000 or

repeating (0).

You can choose external control with

cycle-TRIG.

The measurement cycle is stopped. The unit measures in

mass-MODE:SAMPLE

(even if a different

MODE

has been entered) in the selected channel on the mass

defined with

MASS

(or

FIRST)

at the speed selected with

DWELL

(or

SPEED)

The switching functions are OFF, the signals on

elm, mon

and

are available.

Single channel mode: enter

cycle-FUNCT:CYCLE

and

cycle-MODE:MONO

The unit measures in the measurement channel chosen with

select

. If the channel is

changed in the

run

state the measurement is cancelled and the new channel is started.

MONO

is suitable for measurement tasks in manual mode. A separate channel is

programmed for each task. This means that the parameters are continually avail-
able. You can quickly change the measurement task by changing the channel.

Multichannel mode: enter cycle-FUNCT:CYCLE and cycle-MODE:MULTI

The 64 channels can be programmed with any parameters. The channels located
between

cycle-BEGIN

and

cycle-END

are processed sequentially if they are not set

STATE:SKIP.

It is advantageous to first optimize each channel involved in MONO mode.

With the

aux-COPY

function load additional channels with the parameters of the

first optimized channel. Subsequently you only need to adapt a few parameters of
the individual channels.

To achieve the shortest measuring time the channels with identical detector type,
electrometer range and SEM voltage should directly follow each other.

The measurement cycle time CYCLE-TIME consists of the measurement and
pause times of the involved channels. It is measured by the built-in clock.

The clock starts with

run

, stops with

halt

and is displayed by pressing

cycle

. With

cycles-CYCLES:1

(no. of cycles =1) you measure the time for one cycle.

When the channel is changed in MULTI channel mode the data acquisition must
pause until the new measured value is stable. The pause time is set automatically
by the QC 422 based on

RANGE

FILTER

MASS

SEM

voltage and

detect-TYPE

The pause time is displayed under the softkey

amplif-PAUSE

. If you want to

achieve shorter cycle times or greater accuracy you can optimize it with

amplif-P-

CAL

. The minimum value is 1 ms with

P-CAL:0.0

You can reduce

P-CAL

in each channel until its measured value deviates

inadmissibly. The preceding channel should not have a measured value that is
almost identical, otherwise there is practically no transient response and the value
of

P-CAL

would be too small. Change e.g.

MASS

of the preceding channel by ½ u

to determine whether or not its measured value is without influence on the one of
the selected channel.

With the oscilloscope (triggering on the falling slope of

sync

) the transient

response during the pause can be observed at

elm

and (see also

55).