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b. PC Directly Connection (Figure 10)
Figure 10. PC Directly Connection
Under the case of MFM/MFC directly connects to PC without Flow Readout Box, ±15V power supply with good
anti-jamming should be provided by user itself; connects SET with PC D/A output; connects “Flow Testing” with
PC A/D input; “Signal common” connects signal reference point; low-current “common” and heavy-current
“power common”-down lead separately, and connects together to the ±15V power supply common port.
If users need PC performs “AUTO”, “OFF” and “PURGE” functions, we suggested connection as showing as in
Figure 13.
4.6 Zero Adjustment
It could be zero adjusted in case of zero excursions while the first time operating or a long period operating.
Users could adjust the Zero potentiometer from side face (showing in figure 15) or adjust it while removed its
overall (showing in figure 16). Please note it should be sure that gas flow tube could not be open while zero
adjustment (or shutoff the valves); it should be warming up not less than 15 minutes, adjustment performs after
its zero moving to the stable stop.
There is another external zero adjustment function, while MFC connected with our new zero adjustment
functional D08 Flow Readout box, it could be achieved by zero potentiometer of display panel. The important is
the ranges of external zero adjustment is narrow, when there is big zero excursion happened, it should be better
adjust zero from zero potentiometer of MFC.
Flow Signal Output
Set
Signal common
Valve drive
A/D In
Signal common
D/A Out
Signal common
+15V
Off
-15V
Purge
PC or PLC
(ATTENTION: No “Valve drive”
and “Set” in MFM )
Auto
+15V
-15V
common
power common
+15V
-15V
POWER
COM
0~+5.00
0~+5V
MFC or MFM
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