3. Functionality 647C
24
3.7.3 Mode Selection
MGC 647C V3.0
CH1 CH2 CH3 CH4
ACT.FLOW 0.000 1.750 1.400 0.000
UNIT SCCM SCCM SLM SLM
MODE INDEP.
INDEP. INDEP. SLAVE
INDEX 1
STATUS OFF ON ON ON
00 ERRORS FLOW ON INPUT DIRECT
Figure 16
The Mode Selection defines the source of setpoint for each MFC channel. Possible modes are:
- INDEP = independent
- SLAVE = dependent to the actual flow of another channel
- EXTERN = external source for setpoint
- PCS = external controller
- PID = built in PID controller
- TEST = test for maintenance and installation
3.7.3.1 Independent Mode
In the independent mode a MFC is driven by the entered setpoint which is constant.
3.7.3.2 Slave Mode
In the Master/Slave configuration the ratio between the setpoints of the slaves and the setpoint of
d
, the
the master is kept at the selected ratio of gas composition. If the setpoint of the master is changed,
the 647C also changes the setpoints for the slaves according to this ratio. Additionally in this mode
the master channel governs the gas flows of the slave channels. I.e. the setpoints for the slave
channels are calculated from the ACTUAL FLOW of the master channel according to the desire
composition ratio and transmitted to the controllers, instead of the setpoints displayed on the
screen. If, for instance, the gas flow of the master decreases because of a fault in the process
gas flows of the slaves are also brought down, as can be seen from the ACT.FLOW display. If the
gas flow of a slave is disturbed, however, the composition ratio for this channel is incorrect.
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