MKS 647C, Инструкция по эксплуатации, Страница: 30 / 57

3. Functionality 647C
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3.7.3.5 PID Mode
In this mode MFCs are driven by a PID algorithm (see also menu: PRESSURE CONTROL). This
mode is only available with the PID option.
3.7.3.6 Test Mode
In this mode the 647C generates a test signal, which may be useful for installation procedures.
The test signal is a saw tooth beetween zero and 100% with a period of 4 sec.
3.7.4 Zero Adjustment
MGC 647C V3.0
CH1 CH2 CH3 CH4
ACT.FLOW 0.000 1.750 1.400 0.000
UNIT SCCM SCCM SLM SLM
ZERO VALUE 0.005 -.004 0.002 -.002
ZERO ADJUST EXEC EXEC EXEC EXEC
STATUS OFF ON ON ON
00 ERRORS FLOW ON INPUT DIRECT
Figure 17
To trigger the Auto Zero function, the status needs to be changed from EXEC (executable) to ACT
(active) through the cursor keys. The status DONE or FAIL displays the completition of the
function. The status FAIL indicates that the offset was too large and a new zero value was not
generated. FAIL status may also appear if the channel is switched on. The status ACT appears on
the screen for a very short time, so that it is usually not noticed.
The measured value (the zero offset of the sensor of the mass flow controller) is displayed in the
field ZERO VALUE. In order to correct the zero offset, this value is subtracted from actual flow and
added to the setpoint output. This way the controller gets a corrected setpoint and thus equalizing
the sensor signal’s error.
If necessary, one can enter the zero offset directly.